You might try:
http://csgnetwork.com/multirpmcalc.html I like the bottom calculator as it let's you dial in your exact values. According to this calculator, you should be turning 2417 rpms@65mph. Just another tool for your toolbox.
IMHO you've got a pretty sweet setup....the 3.50 1st gear is going to let you stay in first a little longer than the S10 3.76 1st gear and the .78 is a bit lower than the S10 .72. You'll be able to zip around town in 4th gear and still stay within your torque band.
I'm running a 3.42 with a .72 and a 29" tall tire and 2000 rpm's at 65-70mph (with corrected speedometer). I can drop down to 45 mph in 5th and accelerate back up with traffic without a downshift. The cruise at 70 mph is effortless, vacuum gauge hovers at 14-16" at cruise and 20" at idle. There's plenty left with my tweaked 235 but I'm most comfortable at the 65-70 as I'm running the stock straight axle. The aero on these old trucks wasn't really designed for high speeds, and the air noise in the cab at 75-80 is annoying. Your setup should be a real hoot to drive!!! Have fun!!!
Dave
