"Preservation class" has a lot of latitude, the exact application of which depends upon the machinery in question. It could mean a car that's still wearing all, or most, of its original paint, original interior but with a detailed undercarriage, some touch-up work, chrome & metalfinishing, etc...or...a pre-WW1 bike, that's 1 of 3 known to exist...100% unmolested, other than being lightly dusted with a damp cloth, right down to the faded graphics, ossified tires & leather. Generally speaking, the rarer, older and more significant the machine, the rougher it can be and still be a top-specimen in PC.
IMO, small Hondas of the CT70/Z50 era will be held to a higher standard, i.e. have to be exceptionally clean/well-preserved to be legit PC machines. With a few possible exceptions, such as a `72 K1 "Chrome special" or an `83-`90 (that is virtually undocumented) even modestly worn bikes will be little more than good raw material...to restore properly. They just aren't even close to being unobtainium rare. It is, however, a good thing in that it will tend to keep more nice originals intact, further solidifying these bikes as a marque.
