I think your description of "shuttle shift" on this tractor is a misnomer. I suspect it is Select-O-Speed instead (10 forward and 2 reverse gears). The transmissions in these can be problematic, so you want to thoroughly test it and make sure it works after getting warmed up to operating range. There's nothing wrong with a working SOS transmission, but there's lots wrong with one that is broken or needs repair. Almost nobody wants to touch them. They are a nightmare if they fail.
I had a '64 model Industrial Ford 4000 with a loader and boxblade. It had a 3PH, but no PTO. Many of these industrial models had no PTO, but the one you are looking at might have a PTO pump. Mine had a hydraulic reservoir in front of the radiator and a big pump attached to the front of the engine crankshaft. These tractors normally have big cast iron grill that's HEAVY to lift out of the way, but also provides great protection.
If everything works on this tractor, the $2800 is not a bad price. I paid $3000 for mine and it was a horrible smoker. Even so, I got my money's worth out of it. I was happy to see it leave though when I sold it for $1000 after getting lots of work done. If you don't mind tinkering and the transmission seems okay, I'd consider buying the 4000 as long as it has the 3PH. You'll probably at least have to buy new lift arms and may have to do some hydraulic plumbing to put it back into operation. Just be sure it also has a working PTO if you need that to go along with the 3PH.