EDIT:

I actually ended up getting that Soma track bar, Nitto bullhorns, and a 31.8 stem, plus the shim to fit em. Still decided to get the 31.8 stem, even though both these bars fit the 26 mm stem. The 31.8 clamp keeps my options open for future bars I may want. Plus my current stem is a bit long. Went for something a little shorter.

Thanks, all