The Billings plans don't cover any hull details since the furnish a molded hull in their kit.
I did get to touch the real African Queen this past Fall.
It is located in Key Largo Florida and is owned by the local Holiday Inn owner James Hendricks. The boiler that you see in the movie is sitting in the lobby of the Holiday Inn. (www.africanqueen.net)
Hendricks is not a modeler and didn't seem to know what if anything had been done as far as model plans.
The boat is currently under some restoration and rebuild so that it will pass the Coast Guard requirements for tours and rides in the bay.