Originally Posted by repechage

If your frame is without a braze on mount, then No, a 28.6 mm clamp is required. The Campagnolo 28.6 mm clamps are long gone, all now used or NOS by lucky hunting now. Alternatives would be a 28.6 clamp diameter derailleur from somewhere else. Or a 28.6 mm diameter clamp that provides a braze on style mount to affix your braze on derailleur to. Last would be to shim it, but that is not a choice I would recommend.

Jeirvine's '86 Masi has a braze on front derailleur mount.