Actually, I'm going to say hold off on the leather saddle. For now.
The Selle Italia Monolink is 131 mm, which might work, and is designed to be 'friction free' in the area you need. Competitive Cyclist has a white version for 89.00, and they always take returns.
http://www.competitivecyclist.com/se...edition-saddle
It looks like they have a 'special' where you can get a carbon seat post, high-end mono link saddle with carbon rails for about 300 dollars. Yuck. Ignore those! You can purchase the saddle on sale with no seat post. (heh, I've never recommended anyone on TE use this saddle, most of use can't fit on it. Too bad, cause it's a great saddle otherwise).
Future reference. A Selle Italia Turbomatic might work, even though it's 153 mm, because it's so domed that there is much less seating area than expected. And it's very T-shaped and friction free. It's available both with and without a cutout.
Just to verify: you are measuring the outside distance of your bones, and not the center to center, correct? If it is c to c, then you need something much wider.