46RH overdrive ratio.

For the od gear, I think your over thinking it, a 1:1 final gear with a 2:45 rear would be the same as a 0.69:1 with 3.55 why would treat shifting much different, when you get up to/near cruising speed shift as long your not lugging the engine should be fine, and when at cruising speed I'd engage lockup, I guess I could be wrong I don't have this setup.