What do you mean exactly? You had the engine running, was the car jacked up with drive wheels off the ground and you just went from a forward gear to reverse, forcing it into gear?
I have a feeling the Prince clutch will be stuck like a motherfucker so each and every technique to free it shall be made note of, already researched a few, just need to make sure the four wheel drum brakes are working before I actually try to free it up