Oil line plug/ low oil pressure on cold starts
Update:
I cleaned took apart and cleaned all the lifters and filled the engine with the 5W-30 full synthetic oil. There's still a hint of a tick on cold starts and still takes a moment until it builds oil pressure, but it's quite the improvement! Thanks @Mattax, the thinner oil was great advice and the Winnie The Pooh gif really helped me understand haha. Not sure what you can expect from a Craigslist engine and it might be just that, but the slant 6 that was in there before (80s slant also with hydraulic lifters) didn't really care much about whatever oil was used. Anyways, it's running really well now!
Update:
I cleaned took apart and cleaned all the lifters and filled the engine with the 5W-30 full synthetic oil. There's still a hint of a tick on cold starts and still takes a moment until it builds oil pressure, but it's quite the improvement! Thanks @Mattax, the thinner oil was great advice and the Winnie The Pooh gif really helped me understand haha. Not sure what you can expect from a Craigslist engine and it might be just that, but the slant 6 that was in there before (80s slant also with hydraulic lifters) didn't really care much about whatever oil was used. Anyways, it's running really well now!