I think the whole idea of car crafting, hot rodding; whatever you want to call it is to take the car you want to spend your time and $$ on and personalize it to the way you want it. I'm putting a 5.3 LS based Chevy in mine because Chevy built this motor with 290hp, great flowing aluminum heads, forged internals, and 6 bolt main bearings and slapped them in hundreds of thousands of trucks. I bought a 60,000 mile engine from a 2002 Suburban for $500, added a few speed parts, and ended up with almost 400hp for about $1500. It's a great design engine and the aftermarket has a lot of support for it. If Ford or Chrysler had something better for the same price range, I'd have done that.
If you're restoring something to be original or you just have nostalgic sentiment for the old 40's drivetrains, leave the old flattie in it. I'd like to take some long trips in mine and be able to cruise at 80mph with the A/C on while im looking at that cool 1948 dash layout and look down that football field length hood. In my case, I wanted to get the most bang for my buck, which happens to be a Chevy. If Dodge, Ford, Toyota, or whoever has a better product in my price range for the car I want to build, lay it on me and i'll gladly drop it between the fenders.