Paul, I'm located in Terre Haute, In. Where are you?
600 hrs on motor isn't bad. Not a bad price. Tractor is mid 70's so it's close to 40 years old. Just look for oil leaks. I've had to rebuild hydraulic cylinders. Parts are around $30-40 each. Looks like someone put a John Deere seat on it. That makes it worth more. I painted mine JD Yellow. Check out for cracked rubber hoses and tires.
I checked prices on ebay. 10 year old tractors with 1500 hrs are selling for more than I paid for mine. $10-12k.
The carb on mine has no adjustments. I had to clean mine. 3 blasts of air in the right place cleans carb without taking it apart. One spark plug was fouled on mine. Inspect spark plugs, both should be white. Good sign motor is running clean.
They are very easy to work on and lots of fun too. Let me know if you get it.
To be safe, call Terramite 1-800-428-3772 to make sure they have parts. Keep in Mind you are calling WEST WA. I have to sometimes have them repeat what they are saying. Great people, very helpful too. George