Yes, COPO is Central Office Production Order. It refers to a specially ordered car, typically for racing.
There were Chevelles and Camaros that I know of.
I like the '68s with their small tail lights, but the '69s were supposedly screwed together a little better.
This car is basically a strippie '68 Chevelle, set up for a big block (radiator, springs, etc) with a L72 engine.
The L72 started as the top engine in the later mid-year Vettes.
The L72 was a 427, high compression (11 to 1 CR, domed pistons), square port engine with a 780 CFM Holley as I recall.
It was rated at 450 HP with a solid lifter cam. It was rated at 425 in full size cars (Biscayne) but was the same engine.
Many were sold over the counter to racers.
FYI, this was a lousy street driven engine as it required top octane fuel, frequent valve lashes and did not like low rpm with its cam and heads.
Bur get those revs up and wow! Headers were a huge help to make these engines breathe.