I"m going to make an educated guess here that your water pump is not doing it"s job. If the engine is that hot, and the coolant temp is still showing normal, it may be that your gauge and/or it"s bordon tube have also taken this opportunity to quit.
After we bought one of our 10/60, the tractor would boil just by driving it down a road, the water pump showed no signs of problems, no leaks or anything like that, but when we pulled it apart the keyway and woodruff key that drive the impeller were so worn that the impeller would not turn under load. It"s not the first one I"ve done on 10/60 either... mind they are at least 40 years old now.
Hope that helps, Oli.