Yikes, I just saw your post, grabbed my 3A and was about to open it up to measure when I realized that it has a sheet of film in it already. But you're right 92 sounds about right, and 82.55 is the frame size not the film size.

I'd decided not to try this, but if I hear that the "roll" portion of FP4+ was omitted by accident, and they will make FP4+ in 122 format, I will probably change my mind and get some.