@mike-ansberry Can you check the slide lengths against another?, perhaps it was a special built in low pitch A=439.
I would have no hesitation in cutting to bring up to pitch.
The strangest one I have had was a Chinese C trumpet, the open notes were fine, any valved notes flat, turned out to have a Bb valve block and slides.
If it is of any help I can measure my 55 Recording when I get back home at the weekend.
Regards, Stuart.