Check it out, and if you buy it you have to do a build thread 
http://sfbay.craigslist.org/scz/cto/3583335376.html
http://sfbay.craigslist.org/scz/cto/3583335376.html
I've not heard great things about those old non-Turbo 7.3's but love the idea that it's in the F350 chassis.. Parts galore and cheap!
I guess you mean that the old 7.3 IDI is SLOW and NOISY....however, I'd hope you'ld agree that they are also bulletproof...no?
As the owner of a fleet of ambulances for the past 20 years, I can say that the Type I (truck chassis) would be my absolute last choice if I were looking at buying one for personal use. Yes, they're easier to work on, but that is far outweighed by how damned uncomfortable they are. They drive like pigs and getting a proper suspension setup in one is very difficult. Besides the wimpy power of that NA 7.3, a huge concern would be the E40D transmission that it has...a bona fide piece of crap if ever there was one.
Used ambulances are a dime a dozen and it's very easy to find rigs far, far nicer than that one.