The dashboard is the same size stamping and mounts in the same way for 1947-50 model years. It is not hard to replace the trim and gages. Anyone with a good set of tools, a donor car and a couple weekends could make a switch. For example, removing one bolt takes a steering wheel off and the horn ring/contact assembly from a donor Manhattan (1947 or 1948) will match up with the Kaiser's horn button. My father and brother took out the dashboard from a 1951 Frazer in just a couple of hours when we parted one out.
If the car is titled as a Kaiser, has Kaiser tags on it (complete with WRONG TRIM INFORMATION) and there is no SPEC-FO number on the tag (proper combination of letters and numbers) then it is a cobbled up 1948 Kaiser. Final inspection on the line would have turned the car around without the SPEC-FO information. But dashbords did not go to the line until August, if the factory information on change over (1948-1949 model years) that I have is correct.
Unless the seller can document FACTORY PARENTAGE for the set-up, it's wrong.