I agree know that I think about it, tall gears will be a blessing for road trips, I think the rear end could be 2.76, the rear came out of a V8 duster..
Either way, I would try it first before changing to another gear.
If a 360 can throw my old 74 Charger body down the road, it will have no problem throwing your Valiant down the road. (BTW the Charger was no bigger than 3.23, in fact I think it was in the high 2.xx ratio....)
You can always get a couple of ratios, and swap them back and forth as you want until you figure out which one that you like best...