I would contact Craddock Precision for the barrel. They will probably tell you that 13.5 with a midlength gas system or a 12.5 with a carbine +1“ will be best for reliability suppressed and unsuppressed. They also recommended 1-10 twist when I inquired.
These shorty .308s get pretty violent once you're around 12" in my experience. One of my friends tamed his a decent amount with a JP Silent Captured Spring, I believe the H2 version with one of the stiffer springs installed. May be worth it for you to check it out.