Wow!! That's all I can say...... WOW. NOS, and RARE!!!! Your a lucky dog!
I wouldn't clear coat it. That will make it shine. Just keep in it out of the weather. Honestly...... wax it. That will keep it looking nice. Rub WD-40 on the bare metal to keep it from rusting.
Does that tractor have the rear PTO so you can say it's "run-able"?