I do not live on sloped ground but you will need additional hp to climb any real slope, ask dealer for recommendation. Dealer of mower of tractor.
Though I agree with everything in his post, I wanted to quote this part to draw a different angle to it.
I got (as has been mentioned) an International 1066. I don't know engine numbers but I think it's around 125 PTO hp.
I would have been ok buying a smaller one but this thing only has 3,700 hours on it and it was built in 1973! (my understanding is the original owner parked it and either fell to ill health or....fell.... and the wife sold to the second owner which is where I got it)
None the less.... one reason I'm glad I got something this large even though something smaller would work...
Recall my comment that my understanding is we have the tallest hill in the county here on the farm??
My concern was less pulling the mower UP the hill than being able to stop/control it while going DOWN the hill!!
I didn't want the mower to man-handle the tractor, I wanted the tractor and therefore me in control.
I would LOVE it if it had 4WD but, it doesn't.
I also have a JCB loader/backhoe so I do loader work.... the benefits of 4WD and a loader are nice! I can do things "fine" with my 2-WD JCB but it would certainly have more bite if it had 4WD.
Another side note (not remembering your budget).... I think I paid about $13,000 for my JCB (15 years ago??)
It's "Fugly" BUT functional. I don't care how it looks (looks like it worked in a rock quarry as there are ding marks all over it)
None the less.... I'll put BOTH of those machines up against a new tractor/loader/mower and probably come out cost ahead AND when I'm doing loader work, might out-loader you..... can certainly out-dig you (backhoe will dig a flat two foot bottom at 15 1/2 feet deep) My tractor/mower will probably get beat by a new version of both....
But, I'll have more cash in my pocket (to pay sooner repairs than you might have to pay)
Like many things in life, things can be about a trade-off.
Heck, I've bought and just received an entire wiring harness for the tractor. I'm going to replace entire thing because my dash lights don't work, I've got some buggered wires and I have ZERO headlights. I could probably find/fix the issues but I much prefer to just do it right and replace entire harness. I can hardly wait to dig into it!!
So it helps that I enjoy that kind of task. If you don't enjoy it, then spending more to get newer condition might be a good idea.