You won't find a good answer on any forum because all flat tappet lifters these days are crap. Once all the OEMs went to roller, the lifter manufactures concentrated on roller production and phased out the flats.
When flats were the norm, the cams had better blanks, oil had high pressure anti-scuff additives, and lifters had hard feet. Now we have the wrong oil, softer blanks, and unhardened lifters. That's pretty much a recipe for disaster.
Oil can have ZDDP added with not to much problem, so that's easy. With the cam blanks, I'd probably steer clear of Comp and look more towards Howards, Lunati, or one of the other better names. Comp like to send their production to Mexico and let QC go to shit these days. At this time the flat lifters pretty much come from china and don't have the hardened feet on the bottom like the originals did.
I do have a set of 16 Delco OEM lifters I bought for my boat engine many years ago I might let go of. They are actual Delphi units with the hard foot on them and will have a much better chance of surviving. If you're interested I'll take $100 for them. Pricey I know, but it's cheaper than doing it twice.
