Question? Best way to remove exhaust flange bolts
 

I'm installing a used engine in my '94 Ranger. What's the best way to loosen the two exhaust flange bolts? I already broke two (passanger side) after applying heat & liquid wrench & tapping. The two bolts broke off at the head. Guess now I'll have to drill them out but still have the other side to go. I'll probably just cut the ones on the dead engine as I won't be bolting anything up to them! ;-)