Valve cover alignment

[Boiler Ben]

I am having some issues getting my valve cover mounting holes aligned.  I had trouble getting my Edelbrock intake aligned a while back and the advice I got on the forum to use thicker intake gaskets did the trick.  I should have expected some issues with valve cover holes.  I have Ansen short style aluminum valve covers and am planning to use studs.  When the covers didn't fit on the studs, I opened up the holes in the covers from 11/32" to 3/8", using a drill press and just holding the cover by hand.  It helped, but not enough.  Right now, I have the top 3 studs in place and you can see from the below picture what one of the bottom ones looks like.  I could maybe try going to 7/16" on all of them.  I don't think I could drill off center very well using my drill press.  Any advice?

[blykins]

I'd shape that hole with a die grinder and send it.

[MeanGene]

If you can tie it down on the table of the drill press, you can cut an offset hole by using a small end mill and going very slowly

[Heo]

Well,,,,a few strokes with a round file in each hole would fix it fast

[cjshaker]

Well,,,,a few strokes with a round file in each hole would fix it fast

This ^^^

[cleandan]

It looks to be very close right now leaving you a few good options.
Like mentioned above, file, die grind or whatever, the offending hole to custom fit the application and be done.

Enlarge each hole just a tiny bit more to allow for more movement and alignment instead of just jumping up to a 7/16" hole like you mentioned.

You said you are at 3/8" (0.375) right now... Try 25/64 (0.390), and if that does not work then 13/32" (0.406).
Going up in small increments will get you more movement at each hole and thus act like you have opened up the offending hole more on its own without actually making that hole too big.
Creep up on the fit and it will come out nice.

Using a sharp drill bit and a chamfer when finished should give a factory appearance nobody will ever suspect and will not likely make the cover weak or fragile around the holes.