I don't think you'll be happy with a 16' cutter on a tractor with 62 pto hp. For 15 foot batwings, they recommend at least 65 pto hp - and people use bigger machines than that. It will work, but it will seem over-matched if the crop is wet, or dense, or when you cut going uphill. Five pto hp per foot seems to be a workable rule of thumb. Four or less is not really enough.