Griswold, you mean like this one:
http://www.gunauction.com/buy/7709927 ?
Well, you just might be in luck. Here's the deal. We all know that Pietta makes assorted guns that never were, like .44 Navies and such, well so does Uberti. Obviously in caliber offerings, but also in style in some cases. Enter the 1860 conversions. Both the 1860 Richards-Mason and the Type II Richards are available in .45, .44 and .38. But in the case of the .38, the frame is not stepped and the cylinder is not rebated. It is, in fact, the same frame and cylinder as their '51 Richards-Mason. 1860 barrel and grips, but the middle of the gun is '51. Which of course means it is the same as a '61, and the '60 barrel is already like the '61. The pictures on Cimarron's website, unfortunately, are not correct for these models. They show the same frame and cylinder on the .38 as the .44.
THEREFORE, if you get an 1860 Type II in .38, all you have to do is change the grip to Navy and you have a '61 Navy conversion! It will have the short ejector housing, that's the only difference I can think of. In fact, this is a gun on my wish list. It would be fun to have a conversion no one else has just because they haven't thought of it
I want mine in the longer barrel, which is one more slight difference in that the Type II barrels are 8" and original '61's would be 7 1/2". I can live with that, too
But since you are wanting it in 5 1/2", they are available in that length. FYI, the model number of that one is CA9063.