Sounds to me like your leaning more towards the performance side, so i'd go with the 3.55s. As far as the non sure grip, i've run mid 13s with a open 3.23 with almost no spin at all. Did have soft compound belted tires on it though.
I'd say I am lean more toward performance. However, I've also learned the value of balance. Sounds like you had pretty fond memories of the 3.23, & wjajr seems to think the rpms of the 3.21's wouldn't be killing me if I decided to drive it to an event (say, Reno or Madera or LA).
Hard to say how often or far I'll be driving, since until recently the Dart was just the centerpiece of my garage. I enjoy driving more than most people I know, even when there's no where to go.
Anymore feedback from those who may have had the different gears & what they did like and dislike them for?