8" vs. 9" convertor

Can someone answer my original question.

two different diameter convertors, same stall speed. Which is more desirable?

Too me( and i asked this very question on Moparts years ago) the 8 inch is gonna be more efficient than the 9.5 at the same flash.
I have never used anything but 8 inch in all my street/ strip cars over the years with the exception of a Coan 10 inch years ago, which proved to be a dog when i ultimately swapped it out for an 8 inch.
Dont worry( at all) about heat, simply put a good cooler on it and go have fun.
I think you will be astounded how much better the car runs, with a “ real” convertor