I'd concur on the value, might even be higher. The stock and the rear sight will be the big problems. Chuck's idea of using (even if temporarily) a rifle sight is a good one - 95% of the people couldn't tell the difference from 5' away. And, of course you could resell it when no longer neaded. Everything else is common and resonable.

A question, is the stock drilled for three rod sections in a trinagle, or just two, one above the other? If the latter - which are EXTREMELY rare - you might want to consider having a wood expert restore the front of your stock.

In selecting metal parts, be choosy and get the best color/patina match that you can. It's nice that the bore is good but that is not a huge factor in the value.