Unless you are married to CBI, there are plenty of great barrel makers that will make you a barrel to your specifications. As long as you got the time and money. I dont know why CBI wouldnt make you one either. 1:8 308 barrel blanks are no big deal. Every barrel maker in the world has a 308 reamer. All the good ones have a 300 AAC Blackout reamer, or will get one. They are just waiting for your call. Not sure why you need a bunch of people. A whole bunch of people already own one, or two.

I ordered a Shaw 16" 1:8 300 AAC Blackout Bull barrel from the Gunshack for my Savage .223 and it will arrive eventually. They are behind in delivery but that is ER Shaws fault. Other companies are taking orders for Shaw barrels and they are showing a September delivery. Gunshack is saying June. I doubt it will arrive in June, but I already have a AR-15 300 AAC Blackout upper and it is fantastic with an adjustable gas port I can keep it from cycling with subsonic ammo and suppressed it is as quiet as a BB gun shooting 208 gr Amax. Accuracy is Minute of Pig out to 200 yds, which is what I bought it for.

Good luck.