Bought a nice set of fabbed aluminum valve covers with the long bolt- through design and seems the bolt holes in the head won't let these things work because of the angle of the holes.. Can you only use stock type valve covers with the thin flange with these heads??

no actual exp with those heads but I would surely think the drilled/tapped holes in the head valve cover rails should be straight up.

Hard to tell without some pictures. Aftermarket heads generally have the valve cover bolts drilled and tapped perpendicular to the valve cover rail but maybe Edelbrock built some heads with the bolts at an angle? I've never seen that before but maybe you ended up with a set.

The bolts in factory heads aren't drilled perpendicular to the valve cover surface from what i can tell, but the Edelbrock ones are.
Even though they are just slightly angled, you probably aren't going to be able to use a valve cover like that, that takes such a long bolt.

I used the mopar cast covers. They have been on and off( tried different valve clearances to see if I could pick up any et) several times in the past 3 yrs. No leaks. I used the moroso blue gaskets.

Was able to fenagle them on. Bolt binding on cover the whole time. With the cork gasket and drawn down as much as possible gasket was still loose and not compressed. Probably just end up with the mopar performance black finned ones.

The Indy ones work great.