I am NOT saying don't do it except on the Dragon, convertibles, early Virginians, Darrin and 55's. (Roadmaster)
Soooo, a 55 swap is OK?
No, but understand this is just my opinion. 55's are rare, and last year for a MAKE, not just a series. My only interest in this comment is ethical, not practical.
In the grand scheme of things, few people in the collector world care about 1955 Kaisers BUT if you owned a late 1955 car, and it was a rusty mess and you removed the tag, put it on a 54 Manhattan and maybe the hood, etc and restored it at a lesser cost than the restoration of the rusty car - than the law has an issue with that.
If the buyer paid a premium for a "true" 1955 car and later found out it was a rebadged 1954 Kaiser, then the perception and actuality of value is diminished.
There has been the so-called "last Kaiser ever built" for sale for years for $10,000 or so. Are you buying just the "tag" or the archival aspect of that car? If that "tag" was removed and placed on a 54 Manhattan, would you jump at it ? Would you feel like you own the last Kaiser ever built? Or "just a tag"?
So I think 55's have to be separated out just like Virginians, convertibles etc.