Hot Rods Should i or shouldn't i

Stupid questain but will the extra leanth the blower belt adds to the engine fit without moving the motor back? I had a SBC in my 40 pick up with a stock firewall and it was tight to the radiator, don't think I could of fit a blower pulley and belt in there.
Instead of a blower or a big block how about just building a healthier small block? I had a built 400 in my 39, ran hard enough to be tons of fun and fit as easy as any small block. Biggest issue I had was getting the rear tires to hook on street tires, any more HP and that would of just gotten worst.