Please bear in mind that the original 10" twist was a carryover from the Krag's 220-gr bullet and is considered too fast for gilt-edge accuracy with anything but the very heaviest bullets. The 12" twist is ~ 10% more accurate than the 10" with the 168-gr HPBTs of today, while the 16" twist is still popular with 30- & 32-cal Schuetzen shooters and their 160/180-gr bullets.
I wouldn't be a bit surprised to find that the 14" twist was almost perfect for the 150-gr bullet.
Michael, considering the fact that you already have plenty of conventionally-accoutered 1903 sporters, IMO a good plan would be to thoroughly clean what's already there, then find either a slide or a dummy slide for the 48 (even if only temporarily), then simply enjoy it without changing a thing. No, I don't like the buttplate or the swivels or the scope or the trigger stop or the front sight but that's why they call 'em custom. I wouldn't replace anything (at least not permanently) that didn't scream out to me that it didn't match.
Regards, Joe
