I don't doubt that George Sylvain fought Harry Villeneuve, they were both serious bone crushers in their day, but it seems strange to fight for a Canada vs USA match when they are both from Ottawa. Both of these men were some of the original pioneers of karate and jiu jitsu in the Ottawa area, going to Toronto in the early 60's to learn Chito-ryu from Mas Tsuroka and jiu jitsu from Ron Forrester. They were both heavily involved in promoting the at the time new style of full contact karate, which developed into kickboxing.
Wally Slocki, another great Canadian fighter from way back, said something to the effect that his fighting didn't realy come together until he started training with George Sylvain.
Villeneuve's club is closed, haven't heard anyone mention him for some time, but there are plenty of Chito-ryu based schools in the Ottawa area, in part because of him. To my knowledge George Sylvain never taught much karate, incorporating it into his style of Can-ryu jiu jitsu.