The important question is; What are your going to do with the car once the motor is in it?

I see so many "restored" or "hot rod" cars that sit in garages and seldom see the light of day, that I'm baffled. Why did they spend all that money and not drive the car?

Put in whatever motor in it that will encourage you to get the car out on the road and enjoy it, and let others enjoy it.

Personally, I'd do a mild performance upgrade on a 318 and drive the wheels off of it. A mild, fun to drive, 318 stands a better chance of getting driven than a bone stock 318, or a monster street brawler motor with bad street manors. Gene