Your experience was similar to ours -- our H&C inspector didn't even look at our furnace when we went for our C of O!
We GC'd our house two years ago. The frame is steel, 8" exterior walls with 16 and 22 gauge, and the interior is 5/8" drywall.
I keep telling my husband the only way I'm leaving our place is feet first. I'm more than familiar with new house construction practices -- and the slap and dash work of illegals -- which makes me less inclined to leave all the more...
I'm glad it worked out well for you. It sounds like you built a solid house. Enjoy!