Moo, thanks for sharing, great read.
For what I have heard, the pre-production bikes had several differences to the production bikes:
low cover design, clutch cover design, alternator cover design, cylinder design (everything sand cast), rubber mounted engine cases (sand cast), 30mm carbs instead of 28mm, kick starter, longer brake pedal, grab rail design, skinny high tension wiring, tiny spark plug caps, partly black cables instead of grey, black painted ignition coil, black painted voltage regulator, front brake on the left, etc.
JP, please share the pic