i've been all over the place with 54, 56, 58, 62, 65 and 68T spurs along with 16, 18, 20, 22, 24, 26T pinions.
at the moment, i'm running 22/65, but after the fan job, i was getting ready to drop 26/62 back in.
again, didn't really see a difference in temps on the motor when changing gearing. only time i saw any difference at all was the MMM and batts got a little warmer on 26/56, like MMM =140*F and batts = 130*F.