At that price I would have bought it last week.
IT will be a tough little unit .
I takes a 28" 30" 32" or 34" Murray deck and you can usually find these all over the place.
With a 4 speed manual box & chain drive it is a unit that will last for centuries.
Just remember it is a TRACTOR with a continous mesh gear box so you select the gear you want to use while stationary then use the clutch to adjust your ground speed.
Any attempt to change gears while moving will demolish the box.
IT should have a 7000 series Peerless box in it and there are a lot of them around as well.
As Darly mentioned, service items will be fine but mower specific items like deck lift mechanism & hangers will be a "make your own item"
However the trailer is worth the asking price all by itself.
An elderly customer with the same mower ( locally branded ) had a 12 Hp engine fitted with an electric clutch because we could not get all the replacement parts his mower needed & he is happy as the proverbial pig in poo.
He had bought the mower new when they first moved onto the 5 acres and was reluctant to part with it.