Hey Panhead -- What year is your pan?
The alternative you proposed is a good one, and I am still thinking of using a 292 inline because that gives it a stock and orginal look while gaining 42 inches. (Thats a lot of inches on motors this small!) If build a hot rod 292 I'll do as you suggest and keep the original motor. I might go through it using stock GM stuff, so if I ever want to sell this truck I could advertise it with an all original fresh motor. I may also say screw it all and put a monster 292 in the truck, radicalize the 250 and stick it in some rusty old 4 door sedan for a sleeper just for kicks and grins!