Depends on the configuration. If it has the 3 point arms, I would say $3500-4500. If it doesn't have 3 point arms; I Believe they can be retrofitted, but it would be hard to find everything. Same with rear PTO. Not 100% sure on Massey Industrials, but some of the Case/Fords did not come with pto or rear 3 point. Kinda limited to undersized front-end loader or forklift tractor at that point, and would push price down, maybe to $2.5k-3.5k? Also, I think the shuttle shift would add a bit of value, but I Think it was not equipped with a power shuttle on the MF20; but maybe on a 20C?
Edit; online, looks like between $2500-7000, depending on config/condition/location