I'm reacting more to the fact that you've put forward a choice already and that is the old Sterlingworth you picture. Where you go with it depends on which way you want to go - - and this is often predicated on how much money you want to spend.
Taking a modest route, in round figures and assuming good barrels, figure $275 on rust blue and $175 for CC. Personally doing your barrel prep and polishing your receiver following annealing could tilt these prices in your favor. You would probably need to shop for these prices, but that's all part of the process - -( ask us for recommendations, etc.) Last, keep in mind, too, that I'm theorizing doing this work on a Sterlingworth which carries only modest border engraving. Depending on how extensive receiver polishing needs are, you might have to have the engraving sharpened up, along with the name. All these things cost more.
The wood part has always been the big bad bear for me. If you feel you could work with your existing wood, then removing oil stains, repairing cracks, adding a pad of choice and, as necessary and feasible, bending your buttstock for a better fit followed by stock refinishing might lead to a satisfactory result. If your checkering requires re-cutting, then wood related refurbishments will cost more. Assuming, though, that you can do some of this work and don't opt for a leather covered pad, then $400, not counting re-checkering costs, seems a working figure.
Bore and choke work, action repair, and all the other insideous little things that can pop up are all extra, too. (Jagermeister's input about starting with a gun in good condition makes sense here.) These things just have a way of coming to the surface when you're into the project. But in sum and to provoke discussion, lets say that a thousand bucks put out for competent work and parts should leave you with a very credible gun that will shoot where you point and be a pleasure to look at when the birds aren't flying.
If this approach is too modest, then I'd carefully consider Jon's ideas because he's been there.
