Papa Whiskey - I'm in the same situation as you, in California, wanting a 10mm Commander style 1911.
I can't say anything about Fusion Firearms' ability to assemble STI parts, but based on my experience, I will not be recommending their gunsmithing services.
I contacted them in October 2007, asked a lot of questions about 1911 frames for the project, specified my carry ammo. Double checked all the specs with them, specifically asking about what barrel made sense. Told them I was going to use the gun for concealed carry and emphasized the need for reliability.
Fusion Firearms bought a Springfield 1911, Commander length slide, 10mm barrel, magazines, etc. every part except the grip panels.
In late April 2008 I received the gun. Took it to the range and could not get through two magazines without double feeds due to an unadjusted extractor (spent cases remained in the chamber). I noticed bulged cases and had the range gunsmith look at the gun. The barrel chamber was cut to the point to where there was little case support.
I communicated my dismay at the lack of reliability and the unsafe barrel (emailed the photo above). Fusion's response was for me to use light loads! Things went downhill from there. I was
.
I believe most gunsmiths understand the importance of a tuned extractor in a 1911 and no crafts-person I want to deal with would have released a gun that could kaboom with any cartridge that was loaded to SAAMI specs.
Some have suggested I send it back to Fusion, but what miracle would cause them to go from this to a decent gun?
I'll be mad about this until I find someone else to repair the gun. And it will be someone else.