Biggest smallblock?

someone on another forum i visit from time to time,has a 501 on the way, but it seams like that is realy pushing it, very few heads can realy suport that in a good way...
i think a 408 or 416 is realy the max that has a real meaning with stock heads since its hard to make them realy move enough air to turn any rpm...
i may have got this all backwards but im fairly sure...

for me i have another solution with twinscrew blower forcing air into just 345cui and it will hopefully make enough power to not need more cubes for a while