Just fired it up, warmed enough to level the idle, and went through pulling one plug at a time. Noticeable impact to rpm and no noticeable quieting of the engine. Noise sounds really prominent down low and near the fire wall. Double checked the clutch and no change either. Definitely sounds worse now after sitting and oil psi might have been lower. So no more running it from here on out. Will plan to pull the motor and tear down. It’s my reward for repairing all the intake and exhaust manifolds 
I pulled the valve cover earlier and verified the top end was all good and quiet. Recently did the valve adjust and all the lifters were in good shape and moving properly.

I pulled the valve cover earlier and verified the top end was all good and quiet. Recently did the valve adjust and all the lifters were in good shape and moving properly.