Intake wont fit

FWIW, I never use the end gaskets. Silicone only. If your bolt holes center up correctly without and gaskets at all, then measure the gasket thickness and that's about how much you would need to mill the intake.

Single plane intakes sometimes allow one to look down some of the ports and see if there are any port alignment issues. Unfortunately, you only have the bolt holes to go by on dual planes.