My gut feel based on many years of restoration of Hondas, observation of original bikes, dialogue with other knowlegeable like minded people such as KP and others on this forum, is that Cadmium plating has never featured on Honda motorcycles, certainly post 1960. Bright zinc with various passivations (clear, yellow, olive drab on more  modern bikes,......) tends to predominate except of course for the various chrome plated fasteners (top yoke pinch bolts, handlebar clamp bolts, ets).
Here in the UK cadmium plating has been pretty well impossible to get done  for a great many years  for us hobbyists for reasons of toxicity - not sure what restorers of MUCH older vehicles which would of had cadmium plated parts do. 

Chris R.

Hi Steven
Many years ago I had #1256 / E665 which was known to be factory correct / original. It had horizontal vent carbs on it. Factory assembly pictures show the engines to have the carbs attached BEFORE being fitted into the frame, so engine number rather than frame number may be a better indicator as to which carb types are correct. That said, early engines held back  for re-work and so fitted in later frames may of course end up with later carb types fitted?
Just my observations / speculation.

Chris R.

Yes, I too have encountered those numerous times.  As you say, maybe to reduce paint damage the spring washer would otherwise cause.
Chris R. 

Re-stamped for sure and quite likely a set of die-cast cases too judging by the appearance of the VIN pad.

Chris R.

All the 1020xxx bikes were built in January 1970.

Chris R.

Modified K1 / K2 fenders do not look correct as removing all the front and rear bead to leave only the straight edge bead causes them to be noticably shorter than the original double cut item.
I have a Vietnam replica on my rider sandcast - for the price it is okay on such a bike (which also has better rear shocks, modern tyres,...) which over the last 30 years and 120,000 miles has been in two incidents which damaged the front fender. The Vietnam fender is (for me) however not good enough for a restored bike as the edge bead appears hand formed and the rivets securing the fender to its mounting stay are too large and in different positions as compared to the originals.
Chris R.

Good question!
I have come across levers which have been bent, causing the covering to crack - it can then be peeled off as if it were a plastic "sheath". Older levers seem to go "milky" internally, caused by (I think) moisture getting down between the coating and lever (corrosion of the lever). I have also had ones that have yellowed with age.
I do wonder if the coating is some kind of plastic applied by dipping, which does not bond particularly well to the lever itself.
Having run out of NOS correct levers (never had very many anyway) I recently resorted to using clear 3:1 heat shrink to sheath some levers for a 400- restoration (new end boots fitted after the heat shrink). Turned out okay - way better than no sheathing - though the end result is thicker than the original plastic was. No idea how these will age due to use and time.

Chris R.