Two of us have been trying to complete our engines ( & car) builds but we have no solution to our valve cover leakage (it's bad). The oil leaks on to the cross over pipe & bell housing.We have GN1 (aluminum ) heads with Champion valve covers. We also have Cometic head gaskets. The oil drain back holes at the back of the Cometics restrict approximately half of the drain diameter within the head casting. Oil piles up on top of the head & the assumption is that a lot of the oil volume on top of the head drains back through the push rod holes (we both have RJC oil pans for the necessary oil volume). We have tried numerous different head gaskets & sealers with poor results. The sealing surfaces on both the cylinder heads & valve covers are flat with no obvious leak paths. A dry fit prior to installing the heads may not have resolved this issue (by trimming the gasket metal layer). The rivets were removed from the gaskets and the gaskets were sealed on both sides with hylomar. Attempting to cut the stainless support under the gasket bladder may have wrecked the gaskets. Does someone out there have a combination of gasket, sealer & procedure to stop the leakage? This may involve using a different engine oil. Any help is greatly appreciated.