Hi James
I think you're pretty much set but if, by "section sleeve", you mean the ready made Bock sections that Beaufort sells then I think you need a M8.5 x 1.0mm tap to connect it to the barrel (your 10x1 tap isn't going to work for this purpose). I may be wrong, or perhaps I have misunderstood you, but thats what it says.
And brass can be turned on a wood lathe using high speed steel or carbide tools. Just take light passes and, whist its not essential, a little lubrication helps.
Cheers
Ash