too bad about the previous farmer fixes, but without that I suppose you'd wouldn't have anything
I'd be inclined to try to rebuild them as original, it should be recoverable, and it worked for decades .... of course it'll be a learning experience, and no doubt frustrating, but folks fix worse damage, and now you've opened up the doors you can fab some better reinforcing .... you're faced with repairing the hinge areas regardless of hinges and usually the barn door hinges are the same or real close to the side door hinges which are available from vendors .... also for stops, some GMCs used a simple strap, no need for fancy
Bill