Kevs, be aware of the two different (bayonet) lens mounts Canon bodies used. The F1 and F1N used the FD mount for manual focus lenses. The Elan (US name) up to current digital SLRs were fitted with EOS lens mount. Actually, there was one EOS-mount camera body using EOS lenses which didn't have autofocus capability, but was focused manually.
So, if you're thinking about using any existing Canon EOS lenses with an analog body, don't look at the F1 or F1N, but only bodies using EOS mount.
By the way, I hate the term full frame, 35mm being more accurate. But then, there were some 35mm cameras which were half frame (e.g. Olympus Pen), so whatever. The Hasselblad X used 35mm film too and wasn't full frame. Somewhat like the automotive industry in which I worked as a fuel system engineer for over 30 years. Whenever US colleagues mentioned gas, it was important to check if they meant gasoline or LPG. A number of (costly) misunderstandings took place during fuel system developments.
But I understand what you mean, Kevs, when you mention full frame.