The kit arrived today. The instructions seem clear enough, although I want to have the camera in hand and review the mirror instructions before I start. Nice to see that the long strips top and bottom don't need adhesive.
Funny, my ancient Retina I, with uncoated f3.5 Ektar, has no seals and never did. It uses what amounts to a simple labyrinth to exclude light. I wonder why manufacturers began using plastic foam, which deteriorates over time.