I have a re-man 360, and sure enough the inserts that they used in the head for the exhaust manifold bolts pulled out while I was swapping manifolds. I was able to use Helicoils on 3 of them, but on 1 I cant even get the 5/16" helicoil to hold. What is the clearance around that bolt hole in the head? I am thinking about trying to drill and tap a 7/16" bolt in there, but worried about cutting into a waterjacket etc. Help!!