Canadian Built 74 Plymouth Valiant Questions.

Not too likely a factory build with that configuration. Did you check (or, better, photograph) the fender tag? A few things to remember: (1) This what you saw is a 38-year-old car. A lot of parts can be swapped in 38 years. (2) There were no substantial differences in Canadian-built vs. US-built Mopars for the US market by '74. Most of those differences abruptly stopped after '66. And there weren't many differences in Canadian- vs. US-market Mopars after '66, too.