All Kaiser Specials in 1947-48 used a one-barrel carb, although the Carter model may have changed; the two-barrel was used only on those few Kaiser Customs built with the dual-manifold 6 (first appeared in Spring 1948 as an option, also offered on Manhattans only at the same time).
Outside of the serial number plates, the most notable external change was the script on trunk and hood; mechanical stuff will generally switch ok, but I would suggest you get the 1948 edition of the Illustrated Parts List, as some of the mating parts may need to be changed.
Jack Mueller