JB -- Perhaps you could get someone close who might be an old car appraiser...or a restore shop for vehicles...something like that. Or, maybe an insurance company with old car coverage might have an appraiser for vehicles.
If you have documents showing price paid, your costs too, stuff like that, I would go by that too. Plus your time in restoring it some, the time you spent getting it home, etc.
Maybe get something in writing as to an appraisal.
I have a 1950 Chev. 2 ton, and it is a close original farm truck, and what we see these sell for at special vintage car lots, auction sites, etc. ...is another good source for values. Nowadays, it seems like anything old is a collectible to someone !!

mjd