That's a good group you have going there. I'm not one for doing the reenactor thing either, I ware the uniform for real during the week so don't fancy it at the weekend.
I've attached a photo of some of my guns so you can see how a standard LE rifle sling appears on a Lanchster. The top gun is an original Mk1 (SA209), no welding as everything is screwed in place. It requires a selector knob and change lever to return it to the original Mk1 spec (Only a few hundred Mk1s were made). Middle gun is a Mk1 intermediate gun, that is a gun that has Mk1 parts but was made as a Mk1* (SA12859), bottom is a BOSS made Mk1* (77445)