I ran first the 292 .509 then the 320 .533 with flat tops .030 in the hole with no valve reliefs with the dual springs with no problems! Had about .045 off the 906 heads too! Did a crude check on the 533 it was tighter .060 to .070 but never hit and I drove the crap out of it shifting as high as 6600 but best quarters were at 5800 to 6000
Now on a hydraulic I use solid Lifters and adjustable pushrods?? to check
