Anyone make a Custom Ring and Pinion for 8.75??

I think there use to be a 5.38 for an 8 3/4', but still hard to find. With typical .2 steps in ratios - 4.86 -5.13 - 5.38 - 5.57, etc. I don't think you could get a whole 'step" just by using a 1" or so shorter tire. You can figure it out more accurately with a gear/tire diameter/rpm formula.

Class racers sometimes get together for a volume purchase on custom ratios.

Dana 60 ratios might be easier to find and the efficiency often makes up for the added weight. Good insurance for a Torqueflite.