My $.03 (due to inflation) is to LS swap, but ignore half the stuff you think you know about LS swaps. You do'nt need a 100k motor or to rebuild it unless it's over 300k and you don't know the history. If you can see it run and there aren't signs of abuse (caked oil, silicone coming out of the water pump gaskets, etc.), you will be fine for many years. In my family we've had at least 6 5.3's along with a 4.8, 2 6.0's, and 2 6.2's. None of them have had major issues except one of the 6.2's with a failed AFM lifter at 200k, all of them have run to 200k+ unless wrecked, and a couple have been over 250k when sold, still running fine. One did consume some coolant, probably a cracked head, after 150k. I put a half gallon in every 6 months or so and continued on.
Yes, you will need a fuel system, but it can be simple or it can be expensive. For what you need, the "best way" would be a full set of TBI tanks, lines, etc., swap to the higher pressure pump, and run a return style regulator on a 5.3/6.0. Cheapest way is an external pump and a Corvette regulator with a short return line and a returnless rail on the engine, maybe new nylon line if your existing line isn't up to the task. Take your pick.
2wd is a known quantity on the mounts etc, and mating it to your existing trans has been done before as well. With the right mounts, you don't need a new trans crossmember or driveshaft, and your speedo cable still runs fine. If you are willing to sacrifice a tiny bit of tuning flexibility, the VSS is not strictly needed, or you can spend a few dollars on a pass through cable VSS or an external VSS.
You don't NEED the Holley style kit, you don't NEED braided fuel line, you don't NEED a rebuild and headers (it'll have 300 hp from a stock 5.3, once upon a time a 300 hp 327 was Corvette territory), a cam is nice, springs are fairly easy, but you should have no reason to pull the heads on it. Unless you have a really good machine shop and a lot of recent experience with parts combinations etc, the LS is the better current platform for stock components. All the SBC guys that really knew what they were doing at the aftermarket sources are retiring, same for machine shops. Unless you KNOW it, you are going to be at the mercy of a 20 year old kid reading parts catalogs just like you are, but he's never had a carburetor on anything but a disposable lawnmower. I'm not judging him, I haven't DD'd a carb vehicle either, it just hasn't been part of life for a few years for most people. I much prefer to trust GM engineering and run relatively stock stuff that was computer designed to be easy to work on and last a quarter million miles and hours of WOT redline testing. Along with that, you get a great water pump design that can be swapped in half an hour, a 160A alternator, good power steering, and if you want it, a much better AC system and electric fans with factory style control. I like old stuff, but for something to use consistently, I'd go modern engine in the classic truck for the best of both worlds.
buhbye bunny 
