What PS5 said and...
I've talked to S&W by phone. It is toll free and immediate, unless the gun smith has to call you back. Anyway they aren't upgrading frames as they come in. That would, at the very least, require a new frame. (new SKU too) That amounts to a new gun, with a new s/n. BTW, Ruger offered that conversion as a recall. S&W has done recalls also, but not lately.
The S&W folks are so geared to customer service (for repairs) that they often "rebuild" anything that comes in. And, I have never had anyything done to a gun without getting a phone call from the factory, with estimates, etc. first. They do however correct things like timing, put springs in older hammer noses, and replace worn parts as they see them.
It is the worn parts replacement you'll have to worry about. If it doesn't parallel a S&W action job, they'll likely mis-identify it as a worn part. But, they should have a gun smith talk to you before any work is done... at least they always have for me. That is the generally the person that's going to do the work and quotes your prices (can do some limited dickering). So, a detailed letter, follow-up phone calls, and straight froward discussion with your smith when on the phone usually gets the job done right.
BTW, I've had them call and ask whether they did the action job on a couple of my guns. One was being replaced under warranty. I told them who did it. The gun smith could be heard dry-firing the non-broken one in the background commenting on how nice the action was. It came back just as it had gone in... except for having the forcing cone trimmed, barrel turned, and new cylinder installed. The broken one got scarpped and was replaced by a new gun... with evrything as close to the original as possible... including action job, contoured and polished trigger, radiused hammer, chamfered charge holes, etc. That worked well. I attribute my service to, primarily, talking to whoever is doing the work.