Exellent tractor (possibly) for your needs. It is 2 generations newer, but a direct replacement for the Ford N series.
There is a 640, 650, 660 models, possibly more but rare.
The 660 is best, 5 speed tranny, live pto - 2 very good options.
The 640 is 4 speed, tranny pto.
The 650 is 5 speed with tranny pto.
Five speed is better as you have more gears to pick from to do different work.
Live pto is wonderful for pto work. You can get by with an Over Running Coupler and a non-live pto unless you are blowing snow or baling hay.
All of them have live hydraulics, which is a major improvement over the N series.
The value of the tractor would depend on which model it is - you look below the air cleaner on the cast metal 'shelf' infront of the clutch pedal, and you will find the model # & serial number hand stamped into the cast. It may be light, & may be covered with fresh paint. I would not buy without seeing it, know what you are getting.
Value also depends on the condition of the tractor. Does it have power steering option? A hydraulic port on the rear? each of those cost you $500 to add or more. Will you want these - can be handy. In great mechanical condition, or needing brakes, a valve job, & looking tired all over?
Can be worth $1500, or $5000.
www.ytmag.com is a great place to talk about old tractors, tho the new crowd is kinda drifting there......
--->Paul