i would just put an old style propane system on it. and ditch the gasoline.We were just going to that very thing, on that very model of vehicle. Son bought a 90 F150 from a neighbor with a 300/5-speed, and it had sat forever. We were planning on new tanks (rusted out) and new fuel pumps, and swap a carb setup off of an earlier 300. We had just gotten rid of an intake and carb off of a 240 that would have worked, but in the end, the truck had title problems, and the neighbor was big enough to give his money back, and the project never materialized.
EFI is a thing of beauty, while it's working well. But on 20+ year old truck, a carb is so much easier to deal with, and troubleshoot.