Just go for the B17 Imperial i.e. don't go for the wider S saddle. I think you will find it too wide. I had a B17 on my touring bike and it was fine. I swopped to it from a Finesse (wider S saddle) because I didn't get on with the shape.
Did you mean the B17 Narrow (151mm) because I doubt the 1mm difference (176 vs 175) between the S and the Imperial would make a huge difference?
The S I believe means "short", a shorter nose so you don't get your skirts caught up in it. Otherwise the design is much the same.
I've got a B17 S, and my sit bones rest nicely far from the edges. I also have thighs like tree trunk (wobbly tree trunks
), and the saddle doesn't chafe at all. Though if I cycle in jeans too much, the jeans wear holes that clearly indicates they are being rubbed by the saddle.
Some people hate it, some people swear it's as comfortable as a sofa. I find it rock hard and unforgiving - but 200 slow km later, it's still feels exactly the same. I once did 1200km in 4 days, and every part of me hurt, except where the saddle meets the shorts. So I think it's worth giving it a try to see if you get on with it.