In that style, there are a few nice ones in the Virtual Library. For examples take a look at the pistols by Jacob Kunz, T. Lawerence, and Troxell.
There's not a great deal you can do to improve the lines of the 13/16" barrel. I once took a 15/16" barrel about 10" long, tapered it to just under 7/8", and made the front ~6 1/2" round, then filed in the wedding bands. The finished pistol handled ok, but I got talked out of it before I finished sighting it in. if I were going to do that profile again, I think instead of filing it round I would fade the front section of the barrel (forward of the wedding bands) from octagon to round. If the heavy barrel is 7/8"x.45, you could do the same thing tapering to 13/16.
If you look at some of the posts dealing with converting the small Siler to an English look, it might give you some ideas.