The benefit, in my opinion, is better fuel mileage since the fuel is metered better. Not sure how much better mileage you can expect, as you are still, in essence driving a shoe box. The older pickups are not the slipperiest things on the road. I'm not sure that you well get any better performance with the TBI. Yes, I think a switch from your 88 to your 78 would be a benefit. You'll need to get the entire TBI system, to include the ECM, the complete TBI wiring harness, if your 88 is a small block, you can use the intake manifold, unless your 88 is a big block. You can use the intake manifold from your 78, but you'll need a adapter for the TBI unit. I made my own out of 5/16 inch aluminum plate. If both trucks are small blocks, use the 88 intake as it's already made for the TBI unit. You'll need a higher pressure fuel pump, too. The best thing to do is use all the TBI related stuff off the 88, and that will make it simpler. Maybe a better solution would be to swap the entire engine, wiring harness, and fuel pump from the 88. Your 88 probably has the fuel pump in the tank, so swap the tank, too, and, depending on the mileage of the 88, replace the pump with a new one. Not a super hard project, but lots of components related to the TBI must be used. There are books available that will guide you thru the swap, and YouTube could possibly be a good source for information. You are making a non-computer controlled truck into a computer controlled one. Project will be easier if you have a manual transmission. You could swap the electronic transmission from the 88, if it is electronic. Good luck. If you need any help, mines not running yet, but I think I've done everything right so far. If I haven't covered all the bases, there is probably someone else on this site that can help you more.
