You are talking about header bolts??
Soak it with penetrating oil ..it sounds like it was turning and then broke?
Depending on LUCk, you can remove the top end while leaving the engine still on the Savage, just lowering it all you can for clearance. I personnally now recommend this route, and taking the top end to a machine shop where, if you have some of the header bolt available, they can weld a bit to it, if that doesn't work see below:
When it goes bad.
One of mine broke, below the surface. I tried drilling and an easy out..the easy out broke also. A year later I found a nice guy with an EDM shop, the only way to get it out. Helped him sell his Guzzi as a thank you. The quote for the work ranged from about $150 to $250., but we working out a much better deal for all involved.