I have the older version of that mower, an rm90. It appears of similar construction, but instead of a gearbox, mine has a large diameter pulley and a belt that drives the blade spindles. It is just about indestructible. I power mine fine with 35pto hp on most grass. Like wmonroe said, it is a bit wide if you are trying to do ditches and will scalp some on high spots if you don't pay attention. I once mowed about 4 acres of 5' tall grass with it, I broke the eye bolt that tensions the spring for the belt tensioner, but wasn't too upset- overall I thought it handled it well. With 60 hp, you may even try to find a bigger mower, probably 10-12 feet if it is just finish mowing grass. Of course then you are getting in to some pretty pricey flexible cutters.