Amén.
BY THE WAY. One of the Forbidden lenses for the Canon 7 (and P) is the well known Jupiter-12 35/2.8 FSU lens. It is known to collide with the light baffles on these cameras.
MY experience however, with a '89 version of this lens is that in fact it mounts ok. The rear of the lens barrel/cam doesn't touch the baffles, the edge of the huge rear glass ALMOST touches the top of the film chamber but again does not.
If you ever try that REMEMBER TO SCREW IT IN CAREFULLY, and always looking through the camera back with the shutter opened in bulb setting.
And have your fingers ready for any friction and stop screwing inmediately if so, if in doubt, DON'T do it.
But I thought I had to post my experience, as there are so many variations of these lenses and I always heard it wasn't safe to mount them. There also a JP page showing a P with a J-12 on it.
So I'm afraid I need that P after all to try, bad luck that I must look for a new computer just to be able to play Thief III (Deadly Shadows), a b'day gift from my friends (GREAT friends indeed! 😀)