maybe the potential solution is already discussed in the post':"" overoiling primary chain""2 weeks ago.
Assuming You have the original knuckle heads on it, most top overoiling problems can be brought back to either returnoil restriction,but you checked this, or no good vacuum to retrieve the oil from the heads, any weak link in the ""vacuum chain "" can give the symptons you described, check this:
1 corks sealing correctly in pushrodcovers
2 breathervalvecavity not worn out, especially near the first small hole in the top of it(oilreturnhole)
3 small oilreturnlines on valve bottom covers not clogged?
4 the correct lifters in the blocks, not swiched, or wrong ones, they must clear the return holes on lowest position
5 leaky camgasket at breathercavity
6 the 2 inletbottomcovers must have each a genuine small hole to make it possible air to be sucked in, to break the vacuum in top , this sounds in contrary with the previous, but its correct
Anything that breaks the crankcase/camchestvacuum leaves the oil in the valvecovers, and they will flood because the supplyoil keeps coming( as you noticed)
hope this helps you