IMHO.........
Leave it the way it is for the current classes (10.90, 9.90, 8.90) and make a MPH limit (maybe?)
Make a new class 7.90 (any MPH you want)....call it Super Eliminator!
I would suggest weight breaks by Cu.In, but you don't think there would be honesty issues would ya.........MPH is indisputable.
Or do nothing at all and we will still go racing without question!