here's my two cents worth of nothing;
1969 Camaro dealer order guides did not list 427ci engines, but COPO (Central Office Production Order) Camaro's were factory-built. These included sixty-nine COPO 9560 ($4,160 retail) units with aluminum block "ZL1" 427ci engines, fifty going to Chevrolet dealer-racer Fred Gibb, nineteen to other dealers. ( I believe Fred Gibb returned thirty something of these to be reinvoiced to other dealers, the only time a dealer has ever returned cars to GM ) Chevrolet developed special graphics and trimmed at least two prototypes, but ZL1's sold to the public carried no special exterior identification.
http://www.camarosource.ca/php/camar....php?year=1969
Maybe more details are offered here;
https://www.yenko.net/ubbthreads/show.../page/0#247878
