the only reason you would go with a big cube motor is to keep the revs low, and lots of torque. thats the key to a long lasting engine though...dont make the engine perform at its limits...get a light ass chassis (rx7, 240, fox, miata, civic, s2000 etc etc) and you dont need gobs of power...a mildly cammed 377 with some decent heads, nice converter leaving off a TB could put you reliably in the mid low 10's, not having to spin over 6k and letting you be cheaper on parts if you wanted.