I own a 70 Monte 402/4Speed (w/ build sheet). Some of these cars could have been mistaken as SS cars with the BB.
I also own a 1970 Camaro Z28 "COPO" which many said did not exist. That one also has a build sheet. What makes it a COPO is not the engine, but the tall spoiler. There is a whole story around SCCA racing that made the 70 Z Copo a reality. There are now several documented 70 Z COPO's.
Point being, that the COPO program was not really a HiPo program, just a mechanism to build non standard cars. Every taxi from back in the day was a "copo" car (special paint scheme), many utility trucks were "copo" cars (special brakes).
Your friends Monte's could have been COPO's, but just a fleet order, not necessarily a HiPo COPO.
Pics of my Monte in this thread:
http://www.fgmcc.com/ubbthreads/ubbthrea...true#Post386167
Rich
