Exhaust studs

I did some work on the heads a while back, removed the exhaust studs, cleaned them, and hand tightened them back into the heads. Well, I'm installing the headers and the exhaust studs are being stubborn. They won't come out! The nuts have rusted to the studs, again. One stud actually broke off on the front head. Fark! It was broken flush with the manifold surface. I drilled a hole through the stud, tried a bolt extractor, but to no avail. I drilled a larger hole and some of the old stud thread did fall out. Then my drill bit snapped. Fark again! I wasn't able to get a good hold on it with needle nose pliers. I used a chisel to knock out some more old bits of thread. That was enough to extract the broken drill bit. Finally, I drilled and tapped the hole. I followed that by chasing the threads on all of the exhaust manifold studs. The delay has given me a chance to buy some heat wrap for the headers.