Should I mill my edelbrock performer rpm intake?

I’m no expert but I’d remove the valley pan gasket, set the intake on and see if I could get the bolts to start. If you can get the bolts in, left and right side, you should be able to check the intake face angle to the heads as well as the gaps to give you an idea of where you need to be. My thought is if the bolts go in without the gasket it will align the intake with cylinder heads.