Originally Posted by Tbuggy

you just have to do the math.

71/23=3.08
70/26=2.69 So if you wanted to use a 70 and get the close to the listed 71 you would actually want keep your pinion the same 70/23=3.04

What ratio are you going for?

81t equivalents would be;
81/27=3
81/30=2.7