What is the serial number of your bike? It's kind of a combination of things.
I don't think either the Dura Ace brakes or the Rally derailleur are original to the bike.
I don't see top tube cable stop braze-ons or eyelets, so that says P13 to me, although the fork still has the earlier "English" bend to it.
The changes to the P13 don't seem to have come all at the same time. Your's appears to be a transitional P13(I'll guess '71-'72) that has had some of the components swapped out. The crankset is the Campy triple that the P15 used.
Kurt really is the guy to talk to on this. He's studied it more than I have. Stan Cooper(Scooper) knows a lot about it as does our own Bob Hufford I think.