Hi Patrick,
Congrats on the purchase of your 78.
There is no shortage of Corvette parts supplier, all depends on what your needs are. In Montreal, Paul Versailles' Corvette Plus has been the institution for decades, for parts and service. They recently moved to a new location in Laval right on the Laurentian Autoroute service road just past the 440. Havn't been to the new location but I'm assuming it is bigger and better! And if you need installation as Sergio mentioned, they have mechanics on site that work only on Corvettes.
If you want to order on-line and shipped to you, Corvette Plus will do that (most of their parts come from Corvette America), and also Corvette Depot and Caledon Corvette in Ontario.
If you are doing major restoration and looking for more choice or specialty items, and saving a few bucks, there are all kinds of suppliers in the US who will ship to you. Even with exchange and shipping, you usually come out ahead. I use several but Zip Corvette seems to work best for me.
Here is a little tip, Zip Corvette often has special flat rate shipping of $7.95 per order (black Friday, boxing day, etc.) but for US deliveries only. That's a good time to place an order and have it drop shipped to a parcel service called Pinnacle Parcels in Richford Vermont, a 45 minute drive from the Champlain bridge through town of Sutton. Pinnacle Parcels charges $2 per package to handle and hold your deliveries (yes... $2!!). So you make a day of it, nice drive through the townships, go pick-up your package just across the border in Vermont, fill up your gas tank, pay the sales taxes (no duties) at customs on the way back, and stop for lunch in Sutton.
And if you happen to be driving your 78 to pick up your package, well that makes it just perfect!
Good Luck.