I can’t answer this question, but I’ve purchase light seal kits for several cameras from Aki Asahi, and they have been excellent. They do list the RB67:
I bought the Aki Asahi kit too (for my RB67) and it worked well. Though I have a bunch of film backs and they only gave me enough foam for two. No worries though. I had some extra self adhesive foam laying around and used the Asahi kit as a template to cut more. I thought about cutting my own seals for the whole camera, but the large square ones would have been more difficult to do, so I bought the kit.
Excellent, I'll contact him and get a few kits, anyone got some focus screens laying around? The 45* split image preferrably, off to the marketplace I guess lol