Stop in for a cup of coffee

my wife and the nurse were making fun of me yesterday. I was doing math sitting there to figure out my final drive ratio and rpms now with the t56 vs the 833 which was my first plan.

Im using a 3.23 suregrip 8.75 (for now, may step up to a dana 60 and sell the 8.75)

with the 440 and the 833, assuming a 26 inch tall tire. to run interstate speed of 70 mph, I'd be spinning about 3000 RPMS.

Now same engine and tire, with same rear, using the T56, I'd be running about 1900 RPMS.

Question is now, is that 1900 going to be too low in 6th gear and should I step up that rear gear? The 1st gear ratio is a 2.66:1 in the t56 vs a 2.44 in the the 833.

Tremec has a toolbox App. Allows you to plug in ear trans gear ratio, tire size, etc to figure it out. Or reversed if you know all the other info. It also allows you to use your phone as an angle finder to calculate your pinion angle and such. Free and very helpful.