It's MUCH more difficult to prove that there is NONE of something than to prove that something exists. I can't document this but I saw a 1st gen Bird with a Chevy engine that the owner was absolutely certain it came that way from a dealership in Canada. The guy was so credible that I took him at his word. Since then, I always thought it to be true. I'm going to make a concerted effort to prove that there was at least one 1st generation Firebird or GTO/Lemans that was sold with a Chevy power plant. This will include possibilities like strike built cars and also dealer installed engines. You will never prove that there are none. If you look extensively and find none then there may not be any.