I have a stock K1 for the simple reason that I bought it this way, and I'm old enough to understand it would be a pity to spoil such a gem. But if you start from a bucket or rust, like our swedish friend on the "Saving a CB from the salvage yard", there is nothing wrong with building a good cafe, but as somebody said before, "Go big or go home" (I like this motto, I think I will use it in the future). Building a stocker from a rusted out basket case will consume time, money, and when you have spent your budget, you will still have to spend more time and money. You will never recover your investment, and there are many stockers out there, so there is nothing wrong with making a cafe from it, or at least, a decent-looking bike with an eye of the total expenditure. From my point of view, when you buy a bike that had been lying for years, it was already dead. People give them away for free or for a song for the simple reason that, even when they are worthless for them, they feel somebody could use them. So if you get a bargain, do what you want, but do it with taste. An expensive paint job doesn't match with a rusty gearchange lever or dirty/pitted rims. All the elements in the bike must keep some kind of consistency.
Then, I believe that you must be able to put the bike to stock whenever you want, so if you want to modify something always keep the old parts, or at least buy a spare even if you are not using it today; you may be using it tomorrow. Cafes or cheap bikes are all ok; choppers and bobbers doesn't fit with the CB general design, at least in my opinion.
Regarding modifications, I was more purist at the beginning. For example, I bought my CB350 and it was olive green. It's not a colour that I like much, so I decided to paint it in candy gold, as it was also available at the time. It's true that my bike didn't leave the factory as a gold bike, but is there really any difference? Furthermore, if you are about to paint your bike, why do you have to choose from the available colours? Imagine you are back in the 70's, enter the showroom to buy a bike and the seller asks you which color do you like. You would probably ask wich ones are available, but imagine the seller simply tells you: "describe the colour you have in your mind for your dream bike". Wouldn't have you bought such a bike? So, why not doing it when you are restoring the bike? If the bike is yours, is yours. You decide what goes in and what not. If the rest of the world likes it, perfect, if not, then so be it.
Tom, thanks for your kind words, but believe me: If you spend a couple days with me your opinion would change...
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Raul