I don't think it is a PX-10, because the rear triangle isn't chromed. Some PX-10's had fully painted rear stays, but they were much later than '74. Better close-up photos would help. A PX-10 from this era should have a full DB Reynolds frame and fork. The Reynolds forks from this era had a crown with a raised chromed fillet bar. The crank should be a Stronglight 93. The headset should be Stronglight Competition. There should be no braze-ons except for the rear derailleur cable stop. Are there any Reynolds decals on the frame?