Kaisers are definitely cool, but I'm afraid they would go nowhere as a kit. Personally I would like to see some '50s Buick-Olds-Pontiacs but they would probably suffer the same fate.
The Rolls builds up really nice as well. I"m pretty sure they've both been released separately over the years, the Rolls as part of Monogram's Museum Pieces series of classics from the '30s.
You can see what the others mean about the separate roof section