need purchase assesment help 1987 GN

[hdwizard1]

A good friend is willing to sell me his 87 GN. He is original owner no mods. Car has been parked for 5 years in an unheated garage in Michigan. No problems before it was parked but car was not preped for storage. If the engine is not seized any idea of value for this car. It was a daily driver and has about 80k miles on it. No rust.
Thanks in advance for any assistance.
I also need to now if it is the harmonic balancer that I will be attaching to to attempt to crank the motor and if so what size socket?

 

[John Larkin]

Remove the plugs and put some oil in each cylinder, maybe half a drinking straw's worth (you know how to put a straw in fluid and put your finger over the top to hold it in). The engine should turn over using the nut on the alternator. I think it's 15/16" or 24mm. Just take some larger sockets, a short extension and a long socket wrench/breaker bar. Harmonic balancer bolt is huge, 1 1/8" or 28mm.

If it's nice, it could be worth $10,000.