I see the car has GTL stickers on it so I'm guessing it has been run at some modern SCCA events recently.
Looking at the basic motor specs it would appear to have a fairly serious tune on it. Keep in mind that once you start twisting these motors past about 7800 they wear out fairly quickly. 8200 will probably go all season, 8600 will likely go a 3-4 weekends, SCCA national cars buzzing to 9000 are only good for 6 hours. The bottom ends are stout, the valve trains are what go south. If you keep the motor to 7800 it will go several seasons. I got over 45 weekends on my motor when it was limited to 7800, 15 out of the 8200 rpm motor..........at 8600 rpms it went 6 weekends and running to 9200 rpms I made 3 events before I bent a valve......note it was driver induced, if I had shut the motor off, rather than limping it in, as soon as it started loosing revs it would have been a minor repair.
One thing a I would change right away is the locker rear end, they suck (my opinion) and hinder a low powered car. Granted depending on what H190 is in it a limited slip diff can be as much as $1500 (the roadster units are getting rare).
Note all 4 speed boxes are direct drive 4th, there is a mid close and a ultra close ratio 4 speed. The ultra close box is worth about $500 more than the mid close.
As for price, tough call, without seeing all the spares but somewhere between 3-6K, some of the guys on GT-Racecar might be able to help. Keep in mind that the engine freshen up may have cost more than the car is worth.
These are great cars, they tend to be very sturdy and being lightweight they are easy on tires and fun to drive. I ran mine in SCCA regions for year before switching to a D-Sports Racer but came back to the Datsun as it is still fun and so much easier on the wallet.

Tom