A 400 block, built with B1 heads and a 4.15 stroke or close to that can make 850 hp . If you need more, up to 1050 hp with the right combo with B1 heads. For a somewhat streetable combo, it will be tough to beat 604 cubes, about as big as a BB can go. There are some good heads for small blocks, but they just can't be built big enough

8..603 156 mph best, 2905 lbs 549, indy 572-13, alky