Older touring bikes have their canti studs closer together than the modern standard. I ran into the same issue converting a 85' Nishiki Cresta to 700's. I could never get good braking out of it without using 90's MTB canti brakes. They much more adjustability. This was a vintage build so I wanted to use the original wide profile brakes so I ended building some 27" wheels. Now everything is as it should be.
Long story short, try some 90's MTB cantis.
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