Lunati Retrofit Hydraulic Roller

For 340 blocks, the problem is the large chamfers in the top of the lifter bores. They allow the waist bands of the lifter to be exposed and dumps pressure from the main supply galleries. Well documented.

For others, where the chamfers is not an issue, could be the parts. I also suspect there are a lot of blocks with well worn lifter bores and folks aren't paying attention to lifter-to-bore clearances like they should. Oil will leak out there just as readily as at main/rod bearings with too much clearance. I never have seen folks measure these aftermarket lifters for diameter.

Of course, all this is not helping to answer the OP's question.... sure is drifting off.