yes your right 3/8 tape kit front and 3/8 or 5/16 rear, need to check out how much the glass sits down into the pinch weld. I have been know to back fill the tape with urethane if there is room and press it in and smooth it out with an acid brush or windshield bone.
Cleanliness is very important when working any sealer and glass. you should also use a pinch weld primer before installing the tape to the body. I've been know to use the primer intended for urethane since finding the products for older systems are getting harder all the time.
water test before installing the trim