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...it will probably be harder to match that crank arm with a replacement than it would be to replace the whole crank with something like a Campy New Record, which would be period correct. Whoever buys it will want it discounted for that reason, and the paint dings appear to be fixable, assuming someone knows how to do it.
Again, it's a popular size. I already have an orange one, and I had to fix some stuff on mine, and repair the paint. I built new wheels, but if yours are serviceable, that's a plus. Probably $500-$600 gets it sold, even with the issues you point out. Brake hoods on a bike this old are not usually in good shape, so that goes with the project.
Maybe you could get another $100 bucks because it's a Holdsworth Pro, in a poplar size. With the crank as it is, I don't see it selling for much ore than that.