Howdy TJC,
Sorry to be so long getting to your post..
As for the 4 3/4 inch barrel.. I guess they don't know nobody wants any.. Get that fancy hacksaw going.
Now, to the 45 Colt... it has been available now and then, but not widely available. I have a pair of the Schofield Opentops and I investigated the prospect. The OT cylinder is the same length as the standard 45LC Model P. I know a few folks that have hade the cylinder bored to fit the 45, but haven't gotten to handle the finished product. So.. if you're up to a little shopping and smithing.. they can be had.
Adios,