Vague Steering, How to improve?

My best guess is that you will be able to take some of the slop out by adjusting, but if it's been driven that way for a long time, the gears (and bushings) are probably so worn out as to need a complete rebuild.
I got a 16:1 box for my Dart (also B engined) :) and 195/70R14 tires in the front. It's only really heavy when standing still. Otherwise it feels very firm and responsive, like a go-kart.