Maximum lift?

Thanks for all the info. With a new set of springs & seals the heads could be used as they are. But, the valve job that was done on them 30 years ago (they haven't been used since) probably included knurled guides & I know there's much more sophisticated equipment for grinding the seats these days. Plus, they don't have hardened seats. I've been looking at a couple of roller cam profiles that have in the range of .531 to .538 lift, so I'll probably just bite the bullet & have the guides replaced & cut down, etc.