I'd take em apart, solvent clean them, blow dry, oil them and reassemble keeping everything in order especially as you know lobe/lifter order. I had a 80's /6 w hyd lifters that would get noisy for awhile then get quiet. Psi was good. I just assumed there was a piece of grit in one of them that would move around in the lifter and hang it up on occaision. It was obnoxious but I just tolerated it (a work truck) but I wouldn't in a daily driver