Well, here is my thoughts. Used to pull a 6 row planter with a jd 730 ( about 55-60 hp tractor). You want to pull an 8 row planter with a jd 5085 (say an 80-85 hp tractor). I think your 5085 will lift and handel with out a problem. It may even "play with it". Just have try it and see or kind of ask around and see what other guys or your dealer think.