All-Crop Cylinder width

I was sitting around thinking yesterday...(I know...bad idea!!) and I got to thinking about the different cylinder widths of the All-Crops. For instance, a 60 has a 60 inch header and 60 inch cylinder. On the other hand, a 100 has a 48 inch cylinder and a 9 foot or 12 foot header. With this in mind, how large could a header could the 60" cylinder keep up with? 15'? I'm curious as to why A-C made these cylinders so wide, yet the headers so small.

The N-series rotary effectively had a 38 inch wide throat/concave and could handle 30 ft headers and 12-row cornheads. Your model 60's wouldn't handle too much more due to the drives and the HP of the tractors used.

This is all my opinion...
They designed the 60 with a 60" cylinder to easily feed into the cylinder properly. They found that they could run a little wider head and still be ok with the cylinder so they built a 66 and later a 72. When they designed a 90, they found that the narrower, but larger diameter cylinder would actually accept more crop and not plug as easily. I think the smaller diameter cylinder would have less momentum and thus slug and plug easier.
The think the combines were released in this order 60, 66, 90, 72. The 90 and 72 may have been released at the same time, I don't remember.