AJ's Opinion; what size SBM do I need

What size small block do I need?
The biggest size they come in
Well, an acquaintance of mine had a 502 that he built, but he went overboard on lightening the the internal components, and it didnt last long. Before that, he had a 468 that ran really well, high 9s in a street driven/show quality demon, cover car on MoparMuscle.
Edit: sorry, i forgot. YES, small block mopars.