This is the ebay ad pic, it's still in the back of my car. Definitely looks to be an O rather than a C, but stranger things have happened with die stamps. But, as a back up to your claim, I googled 'Racer Sportif' (as seen on the chainstay protector). Turns out to be a bike store in Toronto and Oakville.

It's missing the head badge, which is a shame. Superbe Pro cranks are in good nick, wheels turned out to be Open 4 CD on Sunshine ProAm hubs, so definitely worth the sub-$40 purchase and short drive to get it. Suntour dropouts and Tange fork ends. Now if only it was 2cm bigger, it would be a good size for me. As it is its probably too small but it's going into the collection to refinish or rebuild over time and see what happens.