Help with value 79 GMC Sierra 35 dually crew

[wolverinemotorworks]

Was wondering what my truck is worth if I end up having to sell it. 1979 GMC Sierra 35 dually crew with 39,000 miles. All original and in beautiful shape. Brand new rebuild of of original 454. Two tone green over white with really nice tan vinyl plaid interior and rubber floor. Cruise, 8 track, A/C, manual windows and locks. I need to wheel it out, fix minor rust on lower front fender, remount rear bumper, and convert A/C to modern fluid. Bed looks like new (was camper truck). Would like to keep it a while longer, but don't know. Was wondering what some opinions might be here.