You never know....
Actually in this case you do know because:
- living in Honda country and working with many current and former honda engineers, including those that used to work at the motorcycle plant in marysville, honda is the most reclusive with their production information often claiming it a proprietary insider secret rather than releasing it. Maybe there is a .0000001% chance honda will have a change of heart but I doubt it and am going to call it that you will never know.
- For a lot of the older stuff they did not keep very good records to being with and for and the 1960's/70's Japanese mfg stuff the records are not in english as well. I have heard from many that when it came to 70's motorcycle colors, they tracked popularity based on what was ordered by the dealers and not what was actually produced and sold. Look at how much care they put into serial numbers between engines and frames (hint: very little) and most countries were using matching serial numbers since the mid 1960's as an anti-theft measure.
- They made 10's of 1000's of these bikes. The serial numbers give that away. They are not rare, and no particular color is any more or less rare than the same year other colors. Some colors are 1 year only while others are multiple year colors so those will most likely be rare. There are some really rare things like the flying dragon paint sets that people could order from the parts department if you want to go that way:
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As for what you want to paint your bike - paint it the color that looks best to you. There is almost no such thing as a "rare" honda. Even with sandcast cb750s they made more of them than some popular models of muscle cars. Just look at what is most pleasing to your eye and paint it that color. Also, I used to buy up spare bodywork in different colors and swap it out often on my bikes. Nothing says you can't do the same.