The two bolts from the each rear motor mount to the flywheel housing are supposed to be safety-wired after tightening. Some folks don’t do that, but when you get those out look for holes in the bolt heads for the wire.
Once you get those bolts loose you may find that the rear of the engine sags, pivoting around the motor mounts. A jack gently applied to the transmission or the radius rod, then tightening the rear engine mount bolts, can rectify that.