The rear engine plate will stay with the engine block and will be loose and floppy once all flywheel bolts are removed.� It is only held in place by these bolts.
You need to make sure all connections to the engine through the firewall are disconnected.� Temp gauge wire, wire connections, accelerator linkage...everything.� Also, don't forget the ground wire from engine block to frame.� Bag and mark all nuts, bolts and screws after removal.� Take lots of photos during disassembly.
No gaskets or seals will be needed when simply separating the engine from the bell housing.
A good way to help gain access to the upper bell housing-to-engine bolts is to support the engine from below with a jack...or above with your crane, then remove the front motor mounts.� Once removed, lower the front of the engine onto the frame motor mount surface.� It will still be difficult to get to them, but lowering the engine will give you more space.
Before final separation, double check again that all items that tie the engine to the Willys have been disconnected.
Edit:� Because you have the removable floor, you may not need to remove the front motor mounts to gain better access to the top bell housing bolts.
Edit 2: Don't forget to disconnect the exhaust pipe from the manifold.

