Of course you can shoot Service Rifle with any barrel length.
Will you be shooting recreationally, or do you intend to be competitive? What do the top shooters use?
No harm in the Wylde chamber, it is a good design and works well.
I suppose the barrel comes with the 1:7 twist. No reason to select that as first choice, for the bullets you will be shooting in SR. Probably won't hurt, but it is certainly not needed.
If you are serious about getting the best accuracy out of your rifle, get a quality barrel. Like any other rifle, a quality barrel really contributes to accuracy.
Given a dependable optic and a decent rifle, conditionning and practice make the most difference in SR shooting.
Its January, the shooting will start in a few months, are you training?