66 Barracuda 273 Intake Manifold options?
Just remember, if you mill the intake surface, the bolt threads will be shorter and you have more of a chance to bottom out and not get the housing tight enough to prevent a leak. Shorter bolts, double flat washers, or double gaskets are your only options. I don't like using taps to clean threads but I do use thread chasers and follow up by blowing out the blind bolt hole with compressed air.