Slant six builders...Lets talk Cams

another related Q about cams.... at what lift do I have to have the tops of the guides machined so the keepers don't crash the guide seals and the tops of the guides?
When I was playing the / game ..with my '71 head..the retainers interfered with the seals around .460 lift.
If you cut the guides for a positive seal...that won't be an issue.