Engine size recommendation

I like the 318 myself...Only because I am in the middle of building one...They have low compression, so you'll need to mill the heads or get a aftermarket closed chamber head like RHS. On mine I'm using a stock bottom end with RHS heads, with hughes 1.5 roller rockers edelbrock RPM cam and lifters & an RPM manifold with a holley 600 spreadbore carb, and dougs headers...I hope this cobbled together parts engine makes 300 HP. I'd be happy with that. lol