Although there's relatively little on him on the web, there's a lot of information on Heise, his inventions, relationship with Henney and his dealership in the recent Henney book. From what I've read, he was a real dynamo - funeral director, inventor, car dealer and much more.
A 1948 Cadillac Series 75 nine-passenger business sedan listed for $4679 (McPherson & McCall's new Series 75 Cadillac book) while a comparable Packard sold for $3450 - $4700 depending on which Series (Super Eight or Custom Eight) one selected ( Dammann's Packard book). According to these sources, a 1953 Cadilac Series 75 went for $5604 while the Packard limo cost $6900. In '53 there were only 100 Packard limos built as against 2200 Cadillacs.