SB rockers hitting springs and retainers

Original Stock 340 rockers came clearanced from the factory, so they must have been close. Deviation from stock must always be checked carefully. 273 mechanical rockers almost never need readjustment, over 100K miles, if up to spec. with up to .470 lift. Higher lift than that, I have little experience. I'm looking at beehive springs and retainers for my next build also.