I've bought and repaired a lot of used machinery.
If it starts, runs, and moves then $1000 would be top dollar but fair even if you have to jump start it. If it does those things and you clean it up a bit then it would be an easier sell - but not worth any more dollars.
Proving that your dad thought it was worth putting a clutch in would sure be a major selling point.
Receipts, parts boxes, notes, or even a good story. Just the fact that he did that job - not an easy job - shows that a competent mechanic thought it was worth doing - and that is pretty important info to a buyer looking at clapped out machines.
Otherwise, it is mostly worth the value of the three point hitch parts,lights, fenders and mounts, and whatever can be unbolted - maybe a total of $400 worth - before scrapping the rest. Anything rusted is scrap.
But I'd put it on Craig's list and see before scrapping it yourself.
Roger