Yeah, just found that page. Looked through the Body Builders Layout Book. It has graphics for the different bodies, and it has the departure angle labeled, but the value is not listed in their tables of dimensions. 
Nothing tested directly with any local Transits. I was satisfied enough for now with my measurements of driveway angle and what we figured out for the rear of the Transit.Curious whether you ever got this angle of departure resolved with your driveway?
What made you decide to go Promaster over Transit? I hear it's a good van but I just can't get past the hideous front end.