Beautiful car. This will probably make you ill, but my Dad and Granddad took apart a 29 chevy sometme in the 30's to use the engine in a home made sprayer.
Never had to do much to the Kubotas. That's why I love them. I had to replace the bucket cylinders on the 3430 due to a bit of misfortune. I found those at Baileys for less than 20% of the dealer price.
I collect and work on old fire trucks. I presently have a 53 IH and a 52 Mack. The IH is for sale and I'm just starting on the Mack. I don't totally restore them, but rather I work to bring them back to original condition. I.e in the case of the IH it has original paint, that while not perfect, I prefer because it is original.
Given that the tractor is for work, even though working the tractor is rarely WORK, I'd be inclined to get something newer that I knew I could depend on. If the fire truck leaves me stranded I get it towed home, but if the tractor quits in the middle of a snow storm its a crisis. Plus I'd rather be working the tractor than working on the tractor.