What you'll need to do is begin stripping down this motor, pull the head, pan, trans etc etc. I had one that had been apart out in the weather, was able to drive pistons out one at a time and eventually saved the motor.
Also I see the ring gear of the flywheel, I used my GIANT Harbor Freight screwdriver to turn my enging over at that point.
Also inspect the side of the block behind the generator for cracks, common to find long cracks in that area, if that's the case the motor is a gonner.
Best of luck
