your tractor will max out at 4 by 5 baler.
At one time Vermeer advertised only needing 40 HP for a 4X5 baler
I can recall the first round baler I saw in our part of the world. It was a Hawk-bilt, and it rolled the bale on the ground instead of cradling it in the belts that Vermeer used. But before that, there was a round bale system used by Allis-Chalmers and didn't use string wrap. It made a small round bale that weighed about 50 lb. A neighbor had one back in the '50's and stored his hay outside thru the winter.Have a Vermeer 5400 Rebel. Pulled with 60 pto hp. Nice baler but would move to a 5410 or 5420 so I could get net rap. Makes a big difference on storage. John Deere makes a good baler but when I was comparing them the deere's were a lot lighter than the vermeer rebel.
If you get a chance go to the Vermeer website and read plus watch the video on baler history as they invented the round baler.
Good luck.