I haven't measured how wide the canti posts are on my Kodiak but I know that the '86 Cresta I had would not accept Tektro CR720's because of how narrow the fork blade was. So, when I upgraded my Kodiak I didn't even bother testing the CR720's and went right for what worked on the Cresta which is the Planet X Frogs Bollox cantilever brakes.
I've had them on for months and am impressed with their stopping ability. Plus, they are highly adjustable and, to me, fit in tastefully with the vintage aesthetic.