tb27272: I wrote a very lengthy reposne to someone else's queston on 620 gearing just a few days ago, and don't want to write it again. Do a search on the MOnster Board using "gearing" and it should pop up.
The 14/43 is a pointless change. But, 14 front with a much larger number of teeth than stock on the back is GREAT. You want to shoot for about 4900 to 5000 rpm at 60 mph in top gear for maximized performance (and fun).