Congrats Ed on just finding one of these tractors. I'm no expert by any stretch so take this with a grain of salt. I've been looking for a LA John Deere for several years now. There's a thread somewhere on here with a few pictures of what I found and bought.
Three important things I noticed right off about your tractor: the serial number intact, the crank and the color. The serial number plate makes it worth more, period. These tractors, as DRobinson noted in an earlier post, are very rare that still have the serial number plate in place. With that you can nail down to the day the tractor went into production and the day it was finally shipped and to where. That may not be important to some but for you to mention buying it as a project for you and your son, I'll bet it will be to you in the long run.
If that is the original hand crank, the value of the tractor is even more. Most have been lost over the years especially so as the generation that owned and used them have died off and the next generation just didn't have the love and concern for the tractor as their ancestors did.
The color of these tractors varied but the green ones were a deeper green than many restorers use. I've seen some of the 1939 and 40 models that originally were red. Even though the paint job it has now is a poor one, by what you said, I'd recommend putting it back that same shade if you keep it green. During the restoration you may find it was a different color originally. If so and particularly so with the serial number intact, paint it back the original color. I was told one place to tell the original color was underneath the cowl / hood. Rarely does the restorer cover up all of the original paint underneath there.
As far as the value, running or not doesn't matter to most who are selling them as they are so hard to find. If you can get this one for $1800 to $2400, I'd say buy it.