I had the same situation and did the following (from an older thread) that allowed me to both use standard modern dual pivots and not to drill. It has worked well so far.

"I had the same thing. Put the front brake in the rear and, then, I put the rear brake in the front. However, instead of drilling out the hole in the fork, so it could fit an extra-long recessed nut, I used a 6mm coupling nut to connect the "front" brake to a regular, 6mm, screw in the back. This way, I had the brake bolt spanning both holes on the fork and I didn't have to drill anything."