Finally, after much research, I found the 61 production data revised Feb. 61 including the AMA Specs and a special supplement for the SS option and 409. Just about all the factory data you could want.
http://www.gmheritagecenter.com/gm-heritage-archive/docs/Chevrolet/1961-Chevrolet.pdf
Other years are available also at the GM Heritage Center website:
http://www.gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.html