what is the best small block and why ?

Big cubes are no good unless you got the heads to feed them. Unless you want a truck engine.

I agree, stay away from stroking it to 400+ cubes and leaving th e heads bone stock.

Stock heads on a 360 even stock don't flow to well, but then again, there not to dismal ethier. Could be worse. If the car was realitivly light and track prep'd, AKA gears, sus penson etc.... stock heads can run low 12's easy with a Hyd. Cam.

Ooooff course the overall package may not exactly be a street freindfly mill for you...