what brakes did you buy? if you were originally changing the brakse to go from 27" wheels to 700c wheels you should have simply gotten the nutted Tektro brakes of the correct reach.
personally I do like the idea of drilling either the fork or a brake bridge to accept recessed nuts. most bridges designed for recessed nuts are correctly reinforced for them. a bridge intended for nuted brakes depends on the two concave radiused washers for structureand support.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk