There seems to be a lot of concern about over-revving these engines. Although I am sure it can be done if you were a lunatic, it just isn't an issue, given the low horse power/low max RPM that these engines produce under even a minor load.
2400-2600 RPM at highway speed is right at the optimal power curve for your engine.
I will bet that you have plenty of gas pedal left in reserve at highway speed at 2400-2600 RPM.
If you change anything, you will lose that.
With a granny first gear and the 3.55, you have the best setup of all for a stock torque tube truck.
The only setup better than that for a 235 would be a T-5 transmission (w/overdrive) and a 3.73 rear axle (open driveshaft).
Carl
