adjusting oil pressure

I do have cork gaskets. I silconed the gasket to the cover as well as around the bottom 1/2 of the head (just 1/2 of the head so I can get the cover back off). I'm also using hold down bars that spread the bolt load out. I have the factory stamped covers. I would like to use more rigid AL ones but I don't have room w/ my custom headers. I'm not over-tightening the bolts... barely get them snug. I resnug them every other time I run the motor. The covers seal for awhile but eventually become saturated and start leaking again.

Someone told be I can put a restriction in the PCV hose to cut down on oil getting to the carb. I'll try that.