Try restricting oil to the top end. Also check cam bearing and lifter clearances. Lots of areas to drop pressure there. Another thing I have seen is lifter bores that are out of square to the cam. Causes some weird things to happen. The only fix without replacing the block is to Bush the lifter bores.
Yes. I agree. And your advise is appreciated. I have been thinking the lifters could be the issue. But there hydraulic flat tappet. I have run this engine with the valve cover off and it’s not throwing an excessive amount of oil to the rockers. It’s just send drips off a 2500 rpm. So that looks right. I the first engine build I went with a roller cam. Then I installed the roller lifters in back wards so the oil hole was exposed to the oil gallery. That flooded the top end. I correct this and then found a low out pressure issue with the engine. I actually ran that engine some and it lost most of its oil pressure. I pulled it out and the mains were shot. Interestingly, the rod bearing looked totally fine. There the 2.5” Ford rod journals. Not sure how a Chevy 2.3” rod bearing would hold up. All I can figure that the centrifugal force of the crack kept the rod oiled. So the crank was shot and main saddles got hot too so I had all that reworked. I then said screw it and installed hydraulic lifters in this engine. And buy the way the roller cam was restricted to one side of the lifters. I took the restrictor out for the hydraulic lifters. Could I be crushing the hydraulic lifters with to much valve sling force causing the problem? Would sold lifter be better? The lifter holes in the block look good. I would guess the block is really low miles. It was a roush built engine for a factory ford racing team to use in there prerunner. And that’s where the old oil pump came from that worked so well. And btw, it was just a normal melling pump. It look totally normal. When it broke off I tossed it in the scrap pile. I had no idea at that time I would waste the next 2 years chasing my tail.