I've never cut and baled hay, so I can't comment on that. I do have a few different tractors for my 68 acres, and I will comment that if you cannot find parts for your tractor in a timely manner, it's totally useless. What happens if the older tractor has the fan break off and destroy your shroud and fan? I had that happen on my Case dozer, and it cost me $2,000 for used parts from a salvage yard a thousand miles away. I was broke down for over a month.
I like the idea of older tractors. More then once, I almost bought an older tractor. One day, I still might, but only as a backup tractor that I do not have to rely on.
For doing as much work as you will be doing, you need to decide what you are going to do with that hay. Are you going to sell it, or keep it for yourself? If you are going to sell it, who will buy it? Horse people want really clean hay. I have horse and it's very hard to find good quality round bales. Are you going to make square bales or round bales? Where will you store them? Round bales will start to rot if left out in the weather and decrease in value. Square bales have to be stored in a barn. How will you get the bales to the barn, or loaded when you sell them?
You really need to be looking at newer and bigger tractors. The smaller the tractor, the longer you will be on it, and the fewer things you will be able to do with it.
I'm currently waiting on a brand new Massey Ferguson 4707 4x4 cabbed tractor. There are just too many days when it's either too hot or too cold to be out on my open station tractor, that I could be getting things done if I had a cab. 70hp will be enough to handle any sized round bale and run a 12 foot batwing mower. Those are my two main requirements.
For your place, I think you need to be over 100hp