I think that is the answer, you can note from my Cant's the pivot bolt is much farther away from the pad. Your gonna have to go {Retro} this timePeriod cantilevers will do if you can find them, they are designed for closer clearances
View attachment 851495
My Orbit with Tektro/ Shimano mash-up brakes
View attachment 851504
and a 1970's frame with some 80's DiaCompe
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Need a pair to match that front end though! $$You need the sort of cantis that have the old style brake bad, not ones that bolt on
Shimano STX, Alivio, XT, LX, DX etc, rears can catch the heel though if not the 'low profile' type
These look rather sexy
https://www.ebay.co.uk/itm/11389352...Vcwd8X1ag42h7SxXOmNoKG5Xz3|tkp:Bk9SR4LquMbzYw