This is a large CI TR engine. No idea what lifters are in it. The vid he sent me the lifters are as loud as hell. Nice guy, but he's gone to the wrong people since day 1. TR owners love to struggle.
I take that as large cu in turbo regal engine.
If so, I am currently taking a '78 Monza wagon out of storage. 231 even fire/sag 4 spd. When I bought it, you could hear the lifters at low rpm from probably 200ft away. It was worn out (leak down @ 80-85%), but ran good w/perfectly clean exhaust. I installed an oil pump plate kit using the heavy bypass sprg. Have not heard a lifter since. Oil pressure hot is 25+@ idle and 45+ at highway speed. 0-40 wt oil. It served as a backup work commuter for 10 yrs. Put in storage in '03 when I bought another new S-10. My old '92 S-10 is still in service w/353k.
A lot of things can make Buick lifters loud. Before I did anything, I would verify the valve train has no slack. Pull a valve cover and try to rattle the rockers.
You probably do not need my advise, dunno-