The 250gr bullet on top of 10gr Unique does 1000fps+/- depending on pistol barrel length, and it is top end max for a Colt SAA in the old reloading books. That load will be safe (although top end) in a New Vaquero, or your carbine.
No idea what that load will do out of a carbine barrel, but I would expect another 200+ fps or maybe more, at a guess. A load with a slower powder would likely give higher performance from a carbine, but not quite so much from a pistol.
All else being equal (and it almost never is) bigger bullets tend to work better.