Great, lets do it.
First, you may want to consider the main that Bill Kneller referenced, particularly if you are looking for something to get started with and as well, if you are planning on upgrading soon. Sounds as if that sail is in "almost new" condition.

As for testing, I would suggest a couple of things. First, put marks on your main halyard and put marks on the back of your boom so that you have reference points for halyard tention and outhaul settings. I would also suggest we test at the beginning of each season.
If you are buying a new sail, your sailmaker can tell you what pictures to take. If you need some guidance, let me know and I'll get the info to you. I don't think my sailmaker would have any issues with doing the comparisons for us. So in the spring, you can e-mail the photos to me.