Stuck Flexplate Bolts

Hey all,

Ive been trying to pull the seized slant out of my 66 dart and have run into a problem. One of the flexplate bolts is very much in the inaccessible part of where the tranny meets the engine and I cannot reach it. I have now lost 2 wrenches trying to get to it.

Are there any suggestions on how to get to it? Is it possible to pull apart the engine in the car, and get it rotating freely? Any help would be greatly appreciated.