To me, the reality is that any car sitting that long will have a tank of what smells like turpentine in it, period. Probably best to just get a new tank and be done with it. A sending unit and strap insulators, too, for good measure. Might hook up the sending unit and operate the float arm to see if the sender's resistance matches what the gauge needs.
Clean the tank/replace the tank, new fuel pump, and carb might be needed anyway. BUT to get things going, some spray carb cleaner to make sure the throttle shaft and such are free and working. Add some gas via the bowl vent to the float bowl to check the accel pump. Throw in some new spark plugs, too. Maybe some new oil in the crankcase, too.
IF having a running car is important, use an outboard motor gas tank and bulb . . . available at many sporting good stores for about $20.00
It's going to need a new rubber fuel line section at the tank anyway, so this is a good time to put new upgraded fuel line back there, ensuring the tank ground fuel line clamp (or similar) is used.
The car is beautiful and unique, but then I can be a sucker for brown/gold tone painted cars. The interior carpet and such look really nice. Underhood is similarly unmolested. All good!
An unusual and low-production option. Spring Special? As the later "Indian blanket" interior option packages?
Unfortunately, "rare" or "low production" don't always equate to more $$$ above the basic value of the car.
Also unfortunately, this generation of C-body might usually max out at $5K for a completely pristine and operational car. In that orientation, the one for $3600 seems reasonable, by comparison. If you still desire to sell "as is", deduct the price of needed repairs (putting the gas tank back in, replacing the fuel pump and spark plugs), but not doing the carb deal at this time. Get it running reliably first and you might determine the carb rebuild, in this case, is not needed. That's with the Holley 2210, other carbs would be different in that respect.
It's a great looking car and one that many would be proud to own. Proceed as you might desire.
Somebody in here want it? Make your offers NOW before "the world" finds out about this gem!
CBODY67