If you have never used a N series - you will find it a very useful machine.
That machine despite being 75 years old looks to be in fantastic shape compared to others of that era. Those rear tires look almost brand new and the sheet metal looks almost perfect.
As for the rims - you will not need to replace those, those will last a good bit longer in that condition, believe me when I say I have seen rims that you could almost see through and still hold air/water!
AS for other parts to that tractor, they are easily had and not overly expensive. If you are looking for a trailer queen then maybe spending money on it would be necessary, but other than the little inexpensive things that tractor will outlast you !!! They were built in a day that were made with real bones and real teeth.
As for the money - in my opinion, $1500 is underpriced! It is worth more than that. The market for these is has somewhat faded a bit over the last 20 years but there are still many of these going for 3k and up depending on the condition, and that one seems to be in very good condition.
I would ask your "friend" what he'll will take it - allow HIM to dictate the direction, if he wants it to stay with the property ( he does not want to transport to his new place) then you have the upper hand.
I find it somewhat hard to "offer" s price on some things that I truly want form others without embarrassing them or myself - once the owner gives up and says .... I'll take "x" for it, then you know where their price range is heading.
Shoot = if you get it for under 2k - you can always sell it and get more back than you paid for it. Then again you may find that old steel is very unique and fun to use. I miss my ol 53 Jubilee - but it could not do what my Kubota can, so it too was sold.