Are you sure it is a Winchester '94?
The engineering of that rifle was not designed to handle a .45 Colt... the carriage and lifter would have to be designed and the lever throw modified. I know of the Turnbull Restoration sets in .45 Colt (very rare, 5 I think, and exceedingly expensive) and the .45 Colt Legacy Winchester '94s. Is your's one of those??
A Winchester '92 (basically a miniaturized 1886 Browning design) possibly could be rechambered for the .45 Colt from the .44-40 Winchester it was designed to handle. The '92 was made in .44-40, .38-40, .32-20, .25-20 and some very rare .218 Bees.< In the '40's and '50'2 some were converted (unsafely) to .357 Magnum.
There are some REPLICA 1892s that were manufactured in .45 Colt in Japan in a limited run of 500 in 2002.
Rossi makes and EXCELLENT Winchester 92 copy in 45 Colt that you can load for all get out. They also chamber it in 454 casull .... and mine runs like a champ.