Carter TQ - VERY rich at WOT...how to troubleshoot?

Haha, no one ever died from embarrassment don’t worry about that! Your adapter setup should work ok on that single plane.
Glad you got it sorted out.
I had secondary throttle binding issue with a TQ once. Ended up being the air cleaner stud I was using at the time, just a threaded 1/4’’ stud. With the air cleaner on & tightened slightly ( not at all over tightened ) was enough to slightly flex the baseplate of the carb and bind the secondaries.
With a factory ‘style’ stud that pushes down slightly on the top of the fuel bowl, no more flex & no more binding.

Edit; Might be worth checking your air cleaner stud as well if you’re secondaries are sticking or binding.