I've had issues with both GN1 and TA aluminum heads with oil drain back. On my next rebuild on a StageII with TA heads, I will drill through the lower aft corner of each head and run a -10 AN hose down to the pan. Can do the same with Champion heads I think.
I usually drill the rivets and spray copper coat on all layers of Cosmetics. At a minimum I smear sealant around the end layers and around water ports.. Never install completely dry as they suggest.