Define "large", please.
I've been running a 72" Muratori for a number of years now, and it has been fine. Usual issues with lubing the pto shaft u joints, and it jumps quite a bit when you hit a large rock, but does a great job of churning up the soil. That said, it's really too large for our use, and I'm looking at a 48" tiller to use with the small tractor.
The 6-7 foot tillers are about the largest I've seen in a Cat I hitch configuration. Any 35-50 hp tractor should run them without problems.
The dealer also had some really large tillers... 8-12 ft. Cat II, much heavier and probably 75-100 hp needed to run them... used in production ag applications, not for gardens and food plots.