BigKev wrote:
I word of advice I can give is not to separate the two manifolds from one another unless absolutely required. If you do, you may find getting the two manifolds block mounting surfaces aligned and squared again is a real pain in the butt, and sometimes requires machining.

Also since the stud in question is through a water jacket, I would worry to much about the metal fragments from the drilling/tapping operation as you can just flush it out.