Well, that eliminates the 16" F-2/F-250 wheels. They won't clear your rear drums. But you still have the 17.5s and 19.5s to focus on. Assuming you still haven't heard from the guy with the 19.5s, which says he's not serious, there are the below two 17.5s that look correct for you.
http://www.ebay.com/itm/151002291451?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
The only hesitation I'd have is that these wheels still have their tires mounted. A couple years ago I had a pair of 17.5s that held air and that I used to move parts trucks around in the barn. A guy, like yourself, needed them so I had the tires removed intending to pass them on to him. What I found was that both had severe inner rust that wasn't detectable with the tires mounted. I ended up junking both. This is one of the unforeseen issues that can be encountered when dealing with old stuff like this. Stu
Edit - my buddy just got back to me and told me his yard sources have turned up nothing. Stu