IMHO, if you have rot showing on the outside of your windshield frame, it will be much worse where you can not see it. If it were me, and you want to replace the weatherstrip, but a new windshield frame, have it painted and a new glass installed. Then buy 8 new stainless steel windshield hinge bolts (this way you can just drill out the old ones that will either break or strip) and then you can just put the new frame in. They like to rot around the glass and under the frame where the weatherstrip sits.
Anywhere you go on the frames ten to get into a lot of work, and they are all in all cheap and simple to install. "if" your old windshield just happens to be broken, you "might" be able to put in a glass claim. At that point, most glass shops would be just fine with putting the new glass in your freshly painted frame.