It looks as though the centre has broken so the inner bolts fixing it to the crank and the outer ones connecting it to the Torque converter have moved in relation to each other. So the bolt heads against the flywheel access holes are all that is transmitting the power. Although there is damage to the flywheel, it doesn't look too bad and I would be inclined to leave it as long as it doesn't have any cracks.
You can either shift the transmission back to gain access or, in my view easier, move the engine forwards. If you disconnect the exhaust downpipes from the manifolds and remove the radiator and viscous fan, you've opened up a lot of space at the front so with an engine crane (and disconnecting the odd coolant hose and electrical wiring), you can unbolt the engine mounts, raise the engine slightly and move it forwards. With it hanging on an engine crane makes the job a lot easier than trying the support the gearbox and transfer case as the shape and uneven weight distribution makes it awkward. The last thing you want it the transmission dropping on you while you are underneath changing the flex plate.