Your choice of FB may depend on if you're going to chase the lands. The 6 Creed is probably going to erode 003 - .005" per hundred rounds. If you're at 2.9" COAL at the lands in a new chamber you have little to no room to chase the lands before you hit the front of the mag, even with the front plate removed. On top of that, I bet you 'll find the new SMK design to be very jump sensitive. The SAAMI reamers for the 6 and 6.5 Creeds have ridiculously long FBs to accommodate factory Hornady ammo which is extremely long in COAL. I would not set up a rifle that I was reloading for based on factory ammo.
Here is a 115 DTAC seated to the lands in a .120 FB. There is a sharpie mark just above the body/ boattail junction and a sharpie mark just below to help you see where the "break" between the body/ boattail junction is in the neck. The break is a little sliver of copper. This is the exact angle between the the body and the boattail.
115 DTAC seated at the lands in a .120 FB. COAL is 2.800"
This a 105 Hybrid seated at the lands. COAL is 2.805".
What do you think a .190 FB with 60 thou erosion would look like?