I would recommend Thomas Top & Upholstery Co., 1317 N Cahuenga Blvd, Hollywood 323-469-3277. They didn't install a windshield for me, but did a fine job with the much harder task of reinstalling the rear quarter windows in the hard top. That takes a lot of experience with 113's, so I'm sure they would be quite capable of handling a windshield gasket as well. I can't remember the guy's name, but it's a small shop, so it should be easy to find the right man.
Chris