I have headspace gauges, a 6.5CM reamer and a lathe, so am not overly concerned. If push comes to shove, I can set the shoulder back and face the barrel tennon to account for any excessive or generous headspace. In the other direction, I have a reamer, so pushing the chamber slightly deeper isn't an issue either.
For me, the big thing is cutting threads (I suck at it). Everything else (with a little bit of set up work) I can resolve if it doesn't fit right.
One of these weekends I need to just park my *** in front of the lathe and practice cutting threads until I'm comfortable and proficient with it.
Carbon Six did offer to install it on the action and check it for something like $60 (IIRC), but, living in California, and them being in Louisiana, doesn't encourage me to take them up on the offer (especially given that I have the tooling I need to do the job, if needed).