A Canadian member (Pedlonardrite) has GM exec relatives that had memories.... But it wasn't conclusive because there wasn't any proof. Contacting Jeff K. would be good. If anybody could get an inside line with the Canadian Documentation Service, they would know for sure. And as far as the Pontiac dealers not having Chevy parts, that's not conclusive. There was a Chevy dealer right down the street that could supply the Chevy engine parts. Dealerships often pass parts back and forth.
One question on this: Why did the big Pontiacs get Chevy engines? Or even more general, why did any Canadian Pontiacs get Chevy engines?