With that 25 inch tire, 3.55s will have you at 63 mph at 3000 rpm and 70 will make for 3300 rpm. 3.23 will give you 70 mph at 3000 rpm and 2600 rpm will give you 60. The best way to tell if you can stand 3.55 at 70 is to drive around in second gear for a short trip at 3300 rpm. This is equal to a 4:1 axle ratio, so you'll pull 60 at that rpm. It makes me crave 4.10 gears whenever I do it with my 2.76's.
