On the surface the 24 ft B, B+, C- or C are all the same length same height and the B + and C are slightly wider. What are the details I am not seeing?
Your statement: "It had the Ford 350 chassis and did not ride as well as the B's that I test drove..." for one. They drive completely differently. Your second statement "...B + and C are slightly wider" is interesting. My B is 76" wide while the Regency "B+" 94" wide per their specs. That's 18 inches of "slightly wider" :B which takes you out of parking between the lines in pretty much every standard parking spot.
Dave