ob - I've thought this barrel could could be a good blank to start with:
https://www.gunpartscorp.com/products/884540
I'm not sure which chamber will best suit your needs. At the risk of stating the obvious, I think the Bentz chamber is considered a "match" chamber for semi-auto rifles. Maybe someone else will chime in. I think it's cool as hell you are able to copy the TS barrel. The collar is removable. Are you able to reuse that?
I actually purchased a tactical solutions barrel about a year ago without a bolt. I was thinking I could find a bolt but since no luck. I have one TS upper complete and wanted a second. So I can swap the bolt I have between the two but I'd sure like to have another bolt. Any ideas?