Hemi Dakota:
Lifter clearance is tough to put a number on.
They need plenty with a cast iron block so they don't gall up and stick.
Too much clearance bleeds off oil but if it runs down on the cam lobes its not all bad.
If your lifter bores measure all good but one, take it to an engine shop that can bronze bush the one hole.
Measure EVERYTHING you buy these days. In our "hi-tech" world some companies are sending more trash out the door.
Duster Dave is being polite about Comp Cams quality falling off. We wont use any single part from that outfit.
Crower has always been our choice in lifters [and rocker arms].
Bronze bushings are the best because you can run them tighter without galling.
Good luck:
MATT