I am pretty sure that in the 1972 era that the Campagnolo side pull brakes were an option on the P-13, but not the P-15 which had center pulls. Many P-15s, like mine, have Campagnolo brakes now, but I do not believe any of them to be original from the factory. It is likely that at least some were dealer installed, though.
Tom Sanders
Lansing, Mi USA