A body 491 1 confirms that in North America at least, this would be a 1949 Kaiser Special. This was the lower end model with fewer options available and less chrome or stainless steel brightwork trim. How it would be marketed in Europe? Maybe it was sold there as a "Manhattan". Locally assembled cars often varied quite a bit from the home market. I know this well from also owning several Studebakers; that the Belgium, Australia, and even the Canadian assembled cars can be quite different from the South Bend Indiana assembled ones. For example, they sold some Studebakers with 6 cylinder engines ONLY outside of the USA, and ALL the USA versions had V8. I have one of those "Canada only" Studebakers.
Here is the link to the Kaiser-Frazer Registry: http://www.eskimo.com/~hhagen/reg/reg.htm
The tag does indeed show that it was a Rotterdam assembled car. The "Priz" is likely the paint and trim (interior), which is likely a different numbering system from the North American made ones. I have the same model car, and here is how it reads on my data plate
Serial No. Body No. PAINT TRIM DR TR AG SCH ITEM
K491-027580 21047 215 111A 2 2 1 135 151
The bodies were made up and stored, then removed when a particular car was built. From this you can see that body was made up some 6500+ before the car was assembled
The paint 215 is Glass Green, and the Trim 111A is Brown Corundel Corderoy. The DR (delivery region) 2 means it was built in the US, but exported 1= US, 2 =exported TR means transmission and is a 3 speed manual but no overdrive. AG 1 is the standard basic Accessory Group. On my car, I have a heater and a lighter, and no other options, not even turn signals. SCH schedule and ITEM item are the production order as it was built, as in which day and which car on the line that day (I think)
There are letter codes in the serial number or body number which show where it was built if not built in Willow Run, Michigan. "R" for Rotterdam, "H" for Haifa, Israel, "T" for Toronto, Canada, "A" for Long Beach, California, "B" for Jackson, Michigan and "C" for Portland, Oregon
What is interesting about this car is that it is a 1949, and there are no other 1949-50 Rotterdam built cars in the registry! The first entry I can see is in 1951