I went into this side project feeling that everything has been encountered by now and am amazed at the responses I'm getting. Seems like perhaps everyone involved has already forgotten. My emails to Corvette vendors go unanswered. Nobody knows what solutions are out there... For now, I have ordered a coupler -- the smooth one, and hope that it will stretch over the BBK oval shaped lip. If it doesn't, the BBK guys say I should heat the original (perfect) coupler and probably permanently disfigure it. Oboy! So at least with the aftermarket one, I know I have one that will accommodate the original throttle body if I choose to get it rebushed and rebuilt (if I am not happy with the BBK one).
Good news is that it's nice to have a heated garage for this project to languish in, and I am in no hurry to get the Corvette on the icy roads for now. I still have a bunch of time before the runs begin. After I do the initial work I had planned, I can go do the fun, dressy stuff -- I have brake caliper paint and valve cover painting to do, and I will shampoo the carpeting before the season is upon us. Anybody have a favorite carpet shampoo they like to use?