I found the address in the vanagon archives: 

Kennedy Engineered Products   
38830 17th St. East
Palmdale, CA 93550
(805) 272-1147

I was looking at their catalog the other night, and the definately
discuss this conversion. I think one problem maybe the size of the 
Mazda rotary engine if you want to keep from cutting some sheet metal: 
the engine compartment size of a Vanagon is
much less than the Breadloafs'.