You will most likely never find any parts book that will list engine repair parts for a Carpenter bus.
It is even difficult to find parts and pieces if you ask for parts for a GM P-30 chassis but that will often times work because it is virtually the same as all of the motorhome chassis of the same vintage. If you ask for a GM P-30 chassis be prepared to provide the GVWR as there were several different GVWR's that used different axles, brakes, and suspension parts.
What you will be able to find are the parts necessary to fit a GM 1-ton of a similar vintage. There is virtually nothing different between the engine and transmission in your Cadet than there is in a Chevy/GMC C/K3500 of the same vintage. Depending upon how heavy duty your chassis is, most of the brake, axle end, and steering components will crossover as well.