In the post above, Daga Boy closes with a suggestion of a .45-70.
If that is worth considering, then consider the .45-90 which has a case length of 2.4 inches and a case capacity of 89.68 grains, just short of the .458 Win Mag at 93.3 .
For the 1886 .45-90 lever action rifle, the COL is 2.88. In my 1886 .45-90, we have reached 2150 fps with 450 grain bullets; there were no signs of excess pressure and the load has proven to be very effective on big game.
With a slightly longer action, the bullet could be seated further out to gain case capacity for more powder or less pressure.
Just trying to help.
Just think, you may come up with a new short-action equivalent of the .458 Win Mag with your name on it!