fire ring diameters of various head gaskets

It's a shame if you have gone into the fire ring area, but the bore size always dictates how far into the chamber you open it up, and not the diameter of the gasket, and it should never be used as a guide. It's possible that it could be salvaged by using the head on a larger bore size that doesn't exceed the fire ring diameter. But again, even if the chamber overhangs the blocks deck, you have really created a poor breathing head because of this issue, and air entering the bore will get blocked and trapped by the overhanging chamber. You will be better suited to start with another head.