max cam lift on stock vortec heads????

[tommie]

what is the max cam lift that can be used with stock vortec heads?

i have heard everything from .420 to .450

what lift cams have people used with stock vortec heads?

i am unsure of what cam to buy at this point,
was looking at an eldebrock performer camshaft with .420 lift on the intake and .442 on the exhaust (i believe)

just tring to get some opinions before i buy

thanks
tommie
70 chev swb (all torn down right now)