Sorry, no anwsers from me -- at least not yet. I am on a similar quest though. I have a Colt LW Commander that has had no modification except light trigger work. I'd like to replace the factory sights with better aftermarket fixed sights and I'd like to remove the plastic trigger and replace it with something better. I contacted SM&A
http://www.colt380.com/ and they got back to me by e-mail right away. I may send my Commander to them.
Post whatever you decide and I'd like to see what you do with this project.