408 vs 600 stroker

Ok, I am looking to build a engine for a Plymouth duster. ( I have neither the duster nor have I invested any money at this moment). Ok so the only thing for sure I know I want about this project, is what ever engine is built will be going in a Plymouth duster. Ok so here is the dilemma I am debating between a supercharged 408 stroker... Or a 440 stroked out to 600.... Or a standard 440 with some form of forced induction running a million pounds of boost (not really). Either way my goal is to have a bad a** car, that I only take out on Sundays, get better than 2 gallons per mile. The only limiting factor is it will have to run on good ol pump gas. What do u think?

Depends on your budget and what you like more...big block or small block?