COPO wasn't an Option.
COPO stands for 
Central 
Office 
Production 
Order & was basically developed so Dealers could order large quanties of Special Fleet Vehicles,at a discount,with larger volume as well as superseding corporate red tape.
It made it easier to process for both parties involved.
Vehicles like Ambulances,Buses,Police Cars,Village trucks etc.,all painted there own colors schemes with options catered towards them and not the public masses.
The High Performance Engine ideas were an after thought.