Running Manifold with 5 bolts

There is a lot of meat to an intake, very rigid. You could probably get away with it. there are a few tricks to get a flush stud out. One new way is to freeze it to loosen it with "freeze off"(like freon in a can) shoot it for about 20 seconds and itll shrink and crack the seize. you can also slot it with a cutting wheel on a dremel and try to unscrew it like a screw. EZ outs work if you can drill a hole in the exact center, sometimes impossible if the shear is at an angle. If you drill it out, you can use a metric size tap just larger than the SAE size and use the one metric bolt. Just use some sealer on the water port back there. They are only torqued 35 lbs if I remember correctly