I doubt there are any dedicated 1924 Newton gunsmiths but I would believe any competent gunsmith could correct your rifle. Is the issue something that would be cured by a light lapping?
You have an interesting rifle. I have seen a few 1924 Newtons and thought their DST was interesting/desirable as it put the primary trigger in a better position and seemed easier to operate.
I have had several 1st model Newtons along with a Springfield Newton in 256 and 30 Newton. Both are great cartridges though unsupported by the gun industry.
When your big Newton is up and running, have fun shooting it.
