Grinding, " diesel " noise under valve covers

I had a Chevy 350 block given to me in my early 20s. Four bolt block already .060 over. Cylinders measured well within spec for taper.....but were an honest .065-.069 over. LOL I broke the glaze and assembled it with those old school TRW 12.5 domed pistons and open Chamber heads. Got like 10.7. It rattled like a 1st gen Cummins cold, but that was a runnin little small block. It toted my 69 Chevelle around with authority. lol