Likely not. Either start drilling or head down to Harbor Freight w/ a 100$ bill in your hand and pick up a new one.

Depending upon where the bolt broke, you might be able to get away with seven. However, if the broken bolt is one of the three around the exhaust valve, you'll blow out the head gasket.

As previous poster suggests, best fix is the drill out the broken and then use an "easy-out" screw extractor. Old Briggs I/C's (1980's) tended to use grade 3 bolts which are reasonably easy to drill. Other fix is to drill oversize to the appropriate diameter and then tap and use a Heli-coil insert.

Earlier, I would have welded something that could give you leverage to the stub that protruded, try to coax some wax or penetrant in to loosen the bolt as it was cooling. I suppose now, if you knew some one careful enough with a tig torch it could be built up again. I would think a little heat would be about the only way to extract that. Maybe if careful enough, find center, drill and tap a 1/4-20 and use that to help retain the head.