In my experience, small blocks are best for decent power while salvaging some fuel mileage. Or even some big power if you are willing to deal with the expense and maintenance associated with a 7500+ RPM motor. As for all out power, you simply cannot beat a big block. In my opinion, in a street strip weekend car, an oval port 496 is just too easy and cheap to spend the extra time and money trying to make the same power with a small block.
Adam