I put a used truck pump in my first turbo conversion. It has been running two years now. The motor was out of an 83 Starion with over a 100,000 miles. I drove it to Pismo Beach and back with a cracked head. It has a new used head on it now, and a new timming set. Same old oil pump and it sounds great.
My black truck has a Melling pump in a fresh rebuild. They come with a piece of rubber that fits behind the plunger. This is to help with pressure at start up?

Well on my way to becoming that eccentric old man in every town.(crazy as a s#@thouse rat) With a yard full of desireable old vehicles that tells you, Sorry they're not for sale..... Someday I'm going to fix them.