I am old enough to remember the 60's and owned or drove some of the muscle cars of that era. Never had a COPO but always liked the idea of a 427 sleeper. Long story short, I found a place in SE WI that specializes in restoring COPOs and just about any 1st gens and anything else but 1st gens are their specialty. Currently have a few in various state of restoration, also has a 69 RS Z28 with dual cross ram and 4 wheel disc all original car on the floor. Beautiful and the paint and body work is incredible and he will work on anything, not just old stuff. If you want a COPO he also build knock-offs.
Place is called Pats. It out on K just 45 on south side just before you get to K. If you guys still enjoy the old stuff, stop by and take a look at the eye candy.