Final drive ratios?

[gtrnav]

Any of our experts on here able to help me with available boxes/diffs for 172 sport. I use my 172 for hillclimbing and sprints, and lose out to the Mk 2 Escorts in my class because it is over geared. What about the boxes from the Kangoo vans, what sort of ratios do they run? I'm not fussed about top speed, I only want it to be quick to 90/100mph. I have a JC5 box from a 53 plate car, running 15" wheels, which is better than the original box, but I still have 130mph top speed!