At 2-3 grand,
I would buy it. The K3 was and still is a great touring bike and the best of the CB500/550 range for two-up riding, which I hate BTW
. Yours look great and here, with those impeccable mufflers, it would go for double that money. The K3 has some typical difficulties, but they can be helped.
Personally I never understood the appreciation of the in my view overvalued "0" series and sandcasts. As if Honda did everything right the first time.
If I look at my own CB500K2-ED there isn't
one aspect I don't like better than the first model CB500. Colour scheme and striping are way nicer imo - I prefer black over hippie colour bikes - and the bike had some technical improvements it needed. Of the CB550 models the CB550(K0) would probably be my favorite and I have asked friends in the US to look for one. It was never imported in Europe. But it's all a matter of taste and
de gustibus non disputandum est.