Probably a new barrel blank is in order to change up to the big pistol caliber. I suspect that the nominal number of about a tenth around the bore on each side might rule out reboring, just my guess on that part. Typically a new blank from a big time vendor is a piece of art.
A new barrel stainless blank is probably in the 200-350 range handed to you from one of the good barrel makers we have in this country. I seem to prefer Shilen, but is just my choice, and sometimes I buy from The BarrelMan on the net that handles Shilen barrels with a bit of discount. Barrel blank choice is kinda personal, lots of good barrel blank makers out there. Kinda depends on what you want in the final product.
The No.1 is a bit fussier than some in work to put a new barrel on. I suspect that a Shilen #4 taper would be pretty close to your factory barrel inletting of your caliber/configuration, so that fitting to the forearm would be a mute point with the #4 Shilen taper. Your smith or yourself will be the final judge of that. The barrel has to be chambered and recess cut for the extractor and timed. The extractor you have might work as is, but other extractors are available for about 10 bucks or so per if that works out easier for you or your smith. You are going up in size a bit with the new pistol case and is rimmed.
In the quarter rib there are four screws and 2 studs. Whether you replace the studs or not is a bit of conjecture. Most smiths will charge 10-20 dollars per hole as they have to be fitted pretty nicely to the rib, especially the studs. The four 8-36 screws have to be tapped into the new barrel blank. Again timing is required of said holes to the action proper.
I have some experience with chrome moly versions of ribs/sights, only done one stainless without sights. If you want added factory iron sights, the rib has to be modified or re-bought with the dovetail section for the rear sight. Ribs from Brownells are 50-60 dollars with/without said iron sight slot. The front banded sight is available as well or used to be, so some looking on the web and verifying is a good thing to do if going that route. If you do procure the front banded sight, it will have to be fitted to your barrel for a hairline fit that everyone likes, they come straight tapered in the band, your barrel is tapered. Like I mentioned, the chrome moly versions of rib/sight are available fairly easily, but one might carefully check for stainless if you want such as stainless was not made as many years.
My guess and my guess only......on the barrel work is about 250+ for the chamber/extractor cut/crowning. So if hiring done, the total job can get up there depending on your requirements. Since you said you have experience in guns in general, just add some of the numbers to keep in hand when conversing about parts or craftsmanship.
I suspect that you know about the limited factory runs(K1a's?) in that caliber, but if newly opened up in your area as legal; said limited run rifles in this pistol caliber might be at a premium when/if said pistol caliber No.1 is found. Maybe so, maybe not; gun market can be fickle.
If you peruse the internet, one sees folks doing No.1's for about 450 if they supply the barrel(probably chrome moly) Stainless over the years seems to be about a 60 dollar premium. Just have to check things out. You will find some that will be a lot higher than that if they will do a No.1 at all, kinda like doing pre64's; time at the machines is money for these guys that make their living at it over the Remington and Savage bolt guns applications.
Sounds like a nice rifle to conjure up, do your homework and it will go good.
Roof
