Interesting line of discussion. 30+ years around these cars and I agree with the methodology that you can base the asking price on the finalized value post restoration. The problem is getting a buyer to agree to that finalized value. The market for these cars is all over the place right now, but let’s take the example of an incorrect date code non-original block/transmission driver quality restoration. Right now in early 2018, that seems to be a $130-140k car at most. If you have a chassis with a good history but incorrect engine and transmission, obvious street to track to street conversion, that’s probably the most you can reasonably expect the car to be worth. If the current condition of the chassis would require $50k to make it a $140k car, no investor will give you $90k for it, you’re looking at offers of $60k-$75k at most, leaving an acceptable margin in the car to profit even in the event of market fluctuations.
I made the critical error of not researching deeply enough this past fall and openly contemplated selling 6S1523. Like you, the Hagerty info seemed an enticing guideline. 1523 needs less than $20k in restoration to be an excellent correct appearing driver, and the car has a papered history back to February 1967. But in this market of buyers wanting “original survivors” no matter the correctness or pedigree, buyers are fierce to the point of being insulting. One offer I received would have been a tidy 20% profit on the cars 1987 sale price, to which I politely declined. The car is currently undergoing mechanicals in my garage and if all goes well I hope to have it in the correct red with white hue next year.
Good luck, don’t over estimate your car’s worth, don’t underestimate the potential for insulting offers.