The Specialized Power comes in 168mm width for the wider bottoms also and is one hell of a saddle, very comfortable. I rode the 168mm and the 155mm (after I broke the first in a crash), it's nice both on a short hard ride or a 300km adventure. Note it should be angled down overall with the front part setup flat (or slightly down if you really want to get really low at the front and keep riding in the drops).
Narrow (or too high, which is a bike fit issue to keep in mind) saddles tend to be harder on the backside for me. There's the "Elaston" version of it which is supposed to be more comfy which has a bit different padding in the sitbone area.
I also got on very well on all day rides (even without padded shorts) on the classic Brooks B17, although I'd probably opt for one with a cutout (the "Imperial") if building a new touring bike. The mechanism in the front for tensioning it with their special spanner isn't top quality, sadly, and I needed to use pliers and a wrench to get it to work after a while on two of them already.
Last edited by Branko D; 08-17-20 at 01:06 AM.