I don't know what kind of luck you will have finding a cab but there were many of these cabs built with just a fairing to provide some protection to a rear facing bench seat, many were also built during the tailboard riding era so used the regular cab and the rest of the crew rode on the back.
The C-cab was built from 1959 to around 1990 with fairly minor changes so you have 30 years or so to cover as far as how the pumper is set up, plus many departments buy used vehicles and have them updated so it will be pretty hard to go wrong with the set up of the pumper. I've seen one built with the body from the old AMT American LaFrance which came out looking very good.
The c-cab was very popular so you will probably do quite well searching the internet for photos, here is one site to get you started that has several vehicles built on the cab
http://www.madisonfiredept.com/apparatus.htm
Good luck and be sure to show your work when you get started, this is one of my favorite cabs used on fire apparatus so I'd like to see it.