Crowns are popular for conversion?
School buses tend to leave service with low miles and good mechanical shape. Crowns, being heavy duty, are likely to be good for more miles. Crowns tend to have spring (not air) suspension, low headroom (in my experience) and a middle engine using some unusual components, which makes them poor choices for “high dollar” conversions, but reduces the selling price and tends to make them economical for “low dollar” conversions. A fair number of people “raise the roof” on buses during motorhome conversion, which involves cutting off the roof and installing extensions on the framing spars and extra sheet metal to cover. See Mr. Sharkey’s and look for his 1963 crown. His roof is maybe a “bit more” than an “easy” roof raise, but it gives the general idea.