The length difference between a 7RM and a 7STW is .350". There isn't a throat difference of that much. A long throat on a 7RM would be in the .200" range. The neck shoulder junction is 2.53" on a STW and would clean the whole chamber up on a 7RM. The neck would clean up the existing throat . If a person was worried about it you could always spin the barrel in a turn to make sure it cleaned it all up.
With a 7LRM or 28 Nosler you could have a stepped neck and/or throat depending on the reamer dimensions. They are longer than a 7RM but only .060-.090" longer unlike the 7STW which is .350" longer. Setting back a barrel 2+ turns to try and clean a chamber up starts to get a bit sketchy because you lose threads and recutting threads almost always ends up with loose threads. The only way you can guarantee a re-chamber has a chance of being decent is to get a clean chamber/throat and that is hard to do without at least cutting off the threads and starting fresh. Many times the throat erosion is too far down the barrel to end up with a clean chamber.
With a 7LRM or 28 Nosler you could have a stepped neck and/or throat depending on the reamer dimensions. They are longer than a 7RM but only .060-.090" longer unlike the 7STW which is .350" longer. Setting back a barrel 2+ turns to try and clean a chamber up starts to get a bit sketchy because you lose threads and recutting threads almost always ends up with loose threads. The only way you can guarantee a re-chamber has a chance of being decent is to get a clean chamber/throat and that is hard to do without at least cutting off the threads and starting fresh. Many times the throat erosion is too far down the barrel to end up with a clean chamber.