Well, you're in Texas so I'd say that's a good thing. The Sun Belt is the best place a car can live for the sake of longevity. I'm assuming this truck has sat for 2+ years so we're just getting started cold. First thing I'd do is siphon the fuel out of the tank that it's switched to currently or the rear tank if so equipped. I'd get you one of those little siphon pumps. If that fuel has turned to varnish, I'd use it quickly. I've found from doing the same thing that the little diaphragm in there doesn't handle varnish well. Once you have every drop out that you can, I'd go ahead and replace the sending unit assembly if it did sit for 2-3+ years. Varnish really tears those things to pieces. If your tank comes down, I'd also flush the lines from where they hook to the pump back and disconnect the small steel line from pump to carb and do it for that one, too. Finally, check the rubber lines at the tanks for cracks. If there are even tiny cracks, replace them. As far as reuse/rebuild/replace, rust is the main factor in deciding that. If it's got no rust, just go about your business. Interior surface rust - consider having it rodded out like they do radiators. If it's got holes, replace it. Once everything is buttoned up, and you've got fresh fuel in it, time to get a battery and change the oil and filter. Last thing, make sure your air filter is clean and your air cleaner isn't full of leaves, acorns, etc. Once that's done, you can go ahead and give it a shot.
Proceeding from here, there are many possibilities as to what'll happen. I've seen carbs gum up from sitting and some not. I've also seen fuel pumps break down internally from sitting and some not. Also, both could work or both couldn't. The least you could do if you can't get it to fire off, is spray some starting fluid down the carb while someone turns the key and at least see if it'll start that way. If you have a no start condition, do this. Look down the carb primaries, move the throttle, and see if you see a healthy squirt of fuel on each side begin the instant you move it. If you do see exactly this, you presumably have a spark problem. If you don't see those squirts of fuel, do this. Check the fuel filter. If it's a Rochester Quadrajet, it'll be located behind the fuel filter inlet on the carb. Be careful, as the metal is soft, and there's a spring in there with the filter. If it's not a Quadrajet, replace the external filter with a steel canister type. Try to start again. If nothing, disconnect the steel line at the carb, attach a piece of rubber fuel line to it, and run it in a bottle. Have a buddy turn it over and see if it fills up the bottle. If you're using a 20oz Coke bottle, it should fill up in approximately eight seconds. If it fills up like you feel it should, it's a carb problem, and it needs to be rebuilt by someone reputable (I can offer you a couple recommendations if you get to that point). If not, disconnect the line going into the fuel pump and connect the inlet to a can of gas. Turn it over and see if your bottle fills up then. If it does, there's something wrong behind the pump (not likely if tank stuff was replaced). If it still doesn't move fuel, replace the pump. This is a pretty comprehensive diagnostic chart in narrative form. It's possible that you may have multiple issues or none at all.
Moving on, if your truck is running, great! If not, make sure that you're getting those healthy squirts of fuel as aforementioned. Assuming you are, we can move to a spark issue. First, inspect for any chewed spark plug wires, and look at the contacts on both ends of the wires. If they're charred or dulled from excessive arcing, buy a new set. Make sure your distributor connector is getting twelve volts when they key's turned on. At this point, if you haven't found anything, it maybe prudent to go ahead and replace all the spark plugs and the distributor cap and rotor. Try it then. If it starts, then you got the problem somewhere in the ignition tuneup. If not, test for spark. You can do this in two ways. Get an inline spark tester from the auto parts store, and test for presence, or remove a plug while leaving it plugged it, ground it to metal, and test for presence AND quality. You should see a bright, snappy, whitish-bluish spark when the engine's turned over. You shouldn't see a weak spark after a tuneup, and if you see no spark, pull the ignition control module out of the distributor, and have it tested at the auto parts store. If there was a problem, it should have been addressed somewhere here. Those are the big failure points right there.
Assuming that we finally got it going, you did the ignition tuneup, and the fuel system is working good from end to end, there are a few more things that I'd do. Check for vacuum leaks. Even one can change how your motor runs, and multiple ones can corrupt how your motor runs. You can do a visual inspection for cracked lines, boots, open ports on the carb and intake, etc. You can also get a can of starting fluid and spray around the base of the carb while listening for a change in idle speed. If you hear one, go ahead and replace the base gasket. Next, I'd get you a laser sighted infrared thermometer and check your warmed up engine temp at the side of the cylinder head. It should be near 160, 180, or 195 degrees depending on the thermostat that's in it. OBD I vehicles need that 195 t-stat, but if yours is a 180, that's perfectly fine. I'm not a fan of the 160* stat, but that's just my opinion. If it's running, in the 200s, there's an issue better addressed now rather than later. I'd do a cooling system flush using a little Prestone flush kit from TLE at Walmart first. Also, check the tube ends in the radiator tank. If they're all gunked up, your radiator could probably use a good professional cleaning especially if there was rust or other junk in there when you opened it up. I would like to think that you still have a copper tube-brass tank radiator in it, and if you do, I'd take every reasonable measure to save it if you get to that point. Other overheat culprits are the thermostat (also an underheat culprit) and water pump with the former being a high priority for replacement should you have problems. While I'd suggest a new thermostat on a daily or frequent driver having problems, the radiator and overall cooling system filth will be of the greatest concern. I didn't address issues with the starter/solenoid or ignition switch, but should you run into any of that, you'll need to do a good inspection of the wires and fusible links to rule out any burned links or rodent tampering. Also make sure grounds are clean and tight and terminals are clean as a general rule of thumb before you assume the worst. A remote starter switch (the kind with a trigger or plunger) is a good tool in those matters. You can hook the starter/solenoid directly to the battery and diagnose between a wiring/switch problem or whether you need to rebuild/replace your starter motor and/or solenoid. Hopefully, you can get it all done with this information and proceed with the rest at your own discretion. Good luck!
