[38Chevy454]

Converting to gas should not be too bad, since there are many 8.1 gas engines around. Are you wanting to stay with fuel injection or simple and carb?

To best of my knowledge, the older 7.4 intakes with TBI will bolt up and that is a pretty easy conversion, not sure of the computer interface vs using the 7.4 computer. The pre-Vortec 7.4 from early-mid 90's are the ones I am thinking.

As suggested by hot rod, you will also need fuel tank and pump changes. That guy that does the conversion is probably the best to talk with. A multi-port fuel injection would be better than TBI setup.