Need consulting with implementation of redesigned Drupal site

I have an existing drupal site that has been live for about 1 year. I am just finishing a redesign and hope to launch the new site in the next few weeks. We currently have very good ranking in Google and others and I don't want to loose that in the transition. I am particularly concerned about it because the entire URL/navigation structure has changed. I've been looking around for some time for information on how to do this properly and the answers are all over the board. My current Dev doesn't have any significant experience with this. I am looking for someone who who has experience with transition to a redesign with respect to maintaining existing status in SEs to consult with us on the transition.

Please contact me if you have the requisite experience and are interested. Thank you.

filkertus@gmail.com