Faced with cutting 3 acres, unless you have plenty of time, I'd be looking for a 30 hp tractor with a 72 inch finish (e.g., Woods) mower on the 3 pt hitch driven by the PTO. Figure $5k-$6k for an older used utility tractor. If that's not in the cards, then minimum 60 inch deck with 20+hp would be next best.
For me, I'd like to keep my mowing time to less than 90 minutes. That's about 1.5 ac with a 50 inch deck on a 1650. Or 3 ac on a 30 hp tractor with a 6 foot finish mower.
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