Shorten Rear Diff - Need a little advice

First, thanks to everyone who contributed to my postings and helping this fledging Mopar newbie :). It's been quite a learning experience, but finally see some light at the end of the tunnel. The Dart is coming together, and the final piece will be the Rear end. Thanks to the many responses, and a trial fit I definitely need to shorten the rear. Through some research, found a reputable shop at a descent price. So the next question, is how much to shorten the tubes, and move the flanges in.

Since they say a picture is worth a thousand words, here's the rendering I'm taking to the shop. However, before I proceed, I wanted to ask for your feedback and any advice on the measurements or placement. For Wheels and Tires, I'm planning on 15" Wheels (8" in the front, and 10" in the rear).



Thanks again to everyone for having such a great forum.

Pat