I am sure others will chime in, but I did have an 1863 with a 44" deck on it. That is what was on it when I purchased it. You just have to figger out what you have, what it was originally on, find what you need to make it work, and go from there.
It will work. Get the mule drive too. Just as the info Lew gave you, there will some parts to change out. I would swap the pulley on the deck to the same size as the 54". You probably need a different belt as well. No sure, but you will probably have to modify the belt cover if it has one.