Interesting thread Loren! Did you end up with a divided or single entry uppipe flange?
I remember RAC doing tons of testing years ago and ended up somewhere similar to where you are now.
I made the .82 choice years ago when Tony had a 0.63, or some aftermarket 0.72 size housing he found. Compared to Tony's car, my 82 housing was bogging in third on tight corner exits and didnt provide enough top end to make up the difference on the straights, so i'd drop back about car length on every tight corner which added up to 2-3 seconds/lap. So it was either shift to second gear and lose time on the 2-3 shift, or bog in third. The 63 was faster simply by being able to stay in third. So I went back to the 63...