Check with Steele Rubber at steelerubber.com  Although they used to be exclusively GM stuff they now have Ford/Mercury stuff as well.  In the catalog I have they show rubber moldings for 70 Montego.  Not sure they have rubber for a 4 dr hdtop but at least it is a starting point.  That is a very intersting car you have being a 4dr with a 429 and a 4 speed.  Good luck with your project.