Great email from the Kirby Museum FaceBook page:
Doug Pratt See page 2 of FF #6. Joe Sinnott always inks from the bottom of a page and works his way up. As you can see, Joe started working on issue #6 with page 2. He stopped in the middle of the page because Treasure Chest Comics had called and offered him a contract. Stan, in a professional and friendly way, told Joe to do what was best for himself and his family, but to let him know as soon as he was available again, and as we all know that happened with issue #44.
Sorry about the poor quality of the scan, this is the best one in my K-files. Thanks a lot to Doug for sharing that anecdote. Hardcore Kirby and comics fans probably heard that story before, but I’m sure that piece of Kirby/Sinnott trivia is new to many non-experts.