Daily Driver Engine 318 vs 360, what one?

A 425hp engine doesnt easily translate to 12+mpg. It also doesnt easily translate to daily driver reliability. My best advice is to get a roller 360 from a late 80's truck/van, talk to the guys here about their bolt on builds and come up with the best plan of attck for just doing bolt ons. Don't set your mind on the 425hp mark. Just build it as fast as you can within those guidelines and I promise you. the car will have plenty of go in her.