360 hydraulic lifter failure
I probably should've disassembled and cleaned those before putting them in the block.
I noticed they seemed to have a problem with bleeding off when I was setting the rockers; more than once I had to prime the pump to fill them up so I got an accurate adjustment. The engine has always sounded like they ALL have bled off at first start but they shut up after the oil pressure pops up on the gauge.
I'll give it a try. If find any trash in it (or if it pumps up after I put it back together), I'll go on and do the rest too.