John,
I have a dumb question. Now I'm really confused. Not that it matters now, but you've mentioned a few times about the "choke horn being milled off". When I buy quick fuel Q750s or Q850s, the main body and carb looks like this. No milling or anything needed. Pretty much bad a** right out of the box from quick fuel with some fine tuning and done. Hit the throttle on a cold day, and wham off you go. Everything is matched on these end-to-end, no mixing of metering blocks or main bodies.
Did you get a 100% Quick Fuel carb, a hybrid, or something else?
QFT Q Series