Conventional wisdom is to go with the regular B-17 if you ride in a more upright position (bar tops at or near saddle height). That works for me.

Still, you might want to measure the center-to center distance between your "sit bones" (with the help of a really close friend, perhaps, or by sitting on something soft that will retain an impression, like maybe damp sand) and check the number against the dimensions of the saddle (the B-17 is 170mm wide, the Narrow is 155, for example; see the Flash site at www.brookssaddles.com for specs).

RichC