The 3-1/4" case was a Winchester case, copied from the Engoish .450 BPExpress round, not a Sharps case, as Sharps never chambered a 3-1/4" length straight case in any calibre.
; Sharps did chamber what was called a .45-120, but it was the 2 7/8" case, also loaded with 100gr and 110gr. powder generally depending on whether the bullet was grooved and lubed, or paper patched and what weight it carried.
: The modern long 3-1/4" case is sometimes difficult to get to shoot well with black powder. I suppose it depends on what your accuracy requirements are. With smokeless powders, it is easier, but there is a lot of waisted space that must be filled with something. Air doesn't work well and can cause other problems as can some types of fillers.
: The 2.4" (.45/90) case will be much easier to get to shoot well than any longer case and indeed, the standard .45/70 case of 2.1" is quite enough at under 24,000psi for any game this side of the Atlantic.