I'm running a 84 inch Landpride finish mower behind my 35 hp tractor and it's probably too big for my tractor based on how heavy it is. My 3pt can barely lift it, and when it does, my front tires come off the ground a little bit. When going uphill, if I lift the mower, I cannot steer because my tires are not touching. I have weight on my front bumper, but not enough.
Having said that, I rarely have to lift the mower. It's weight is supported by four tires, so all I need to do is pull it. My tractor can pull the weigh easily, and my PTO has more then enough power to cut the tallest grass. If it's really tall or thick, I just slow down, or go over it twice. Usually both!!!! If I am maintaining an area and mowing it regularly, it's super fast to cut with. This is it's advantage, when mowing regularly, it's the best thing out there.
I did have a lot of problems with the original factory tires. Eventually I replaced all of them with solid tires from Landpride designed for another model. I had to replace the axles with another sized bolt, but otherwise it was a simple change that has resulted in never missing a day of mowing due to a flat tire!!!