I'd think the bore of a .375 barrel would be somewhere around .365/.366". That bore would easily eliminate any remanants of the interior of a .32 Special barrel. I think the combination of steel qualities, tooling and technique didn't quite work out in that particular barrel. Chances are if everything was repeated at a larger bore, the result would be the same.
Maybe that shop specializes in 35 caliber barrel making, and that's their comfort zone, but most of these shops will just say they can't cut some barrels as clean and smoothly as others. I believe reboring's a good option for a selective project or two, with the possibilty that it doesn't work out. I know many lining and full rebarrel projects that didn't live up to hopes.
