A picture says more than thousand words.... Here they are side by side. The lower is from a 1303 and the upper is from a 1302. I have converted my front arms and roll bar from 1302 to the 1303. Both was exchangebly but the 1303 parts fitted better with the other 1303 parts. The main reason I changed rollbar is that the 1303 bar gives you more room for lager wheels as they are more curved. I am able to run 215/50-16 with original turn radius.
I found a link that helps you figure out what happends when you suspension moves and you lower your car.
http://www.racingaspirations.com/macphersongeometry.php
// Anders