One more factor not mentioned, when speaking of a turnkey type resto, is what model it is and how many options it has.
There's a world of difference in hours between something like a nice complete '65 Satellite non-air, manual everything strippo vs. a '71 Cuda convertible with a/c, PS, PB, power windows, 6way seat, etc, etc... Lots of extra parts to spruce up and get functioning correctly.
Also, extra or more complicated trim & brightwork adds more time.

Rick