Here's a thread of Canadian members. You can PM a bunch of them at once and probably get many choices. http://v8buick.com/index.php?threads/canadian-member-roll-call.245812/ http://v8buick.com/index.php?threads/reputable-engine-rebuilder-in-canada.140068/#post-1077917
gusszgs lives up north of Toronto. You might message him. He has a pretty hard running 464 powerd 71 GS.
Hear this dude in Montreal is building Buickās now..... http://www.v8buick.com/index.php?threads/nick-builds-a-500-hp-455.355209/
Yes, they'd be close by. I spoke with Dave Mongeon a few years ago about possibly getting some work done. Also there's Gran sport Autobody in Quebec that is quite reputable, they do full restos and engines. Apparently guys from all over the world send their cars to them.