I don't know if it was a new or used cam from the pics, but I'm definitely going to say it's shot now and needs replacing.
so my theory? this is a mechanic at a small shop that does a little bit of everything. your buddy didn't even order the kit himself, or if he did, it is a Amazon/ebay grade kit. (read China) i didn't know the standard lifters were that bad, but I've seen many threads about guys buying no name afm lifters sets, drop them in only to have to pull it all back apart again a few weeks later because it still wasn't right. seems the cheap China stuff just doesn't work.
Basically oem or millings is the only stock replacement parts for lifters and oil pumps. high end aftermarket is fine too, but you wouldn't put a set of Johnson lifters in a stock motor.
I've also seen where lifters are listed as ls7 lifters but aren't actually gm ls7. just ls7 style lifters and they forget that part in the title.
good luck.