First post!

So, I recently acquired a 1974? PX-10 frameset on the 'bay and I am a bit confused about the dimensions of the tubing. I've scoured the greater parts of the web, but most of what I come up with involves generic discussion of "old French" bikes.

Sheldon Brown lists dimensions for these "old French" bikes, but I'm not sure that this one falls under these restrictions.

The seat tube and stem diameters are "old French" standard, surely, but what about the downtube? Will I be able to slap any ole Campy shifters down there or will I need a set
of proprietary Simplex shifters? How about handlebars? Assuming I grab a proprietary stem
will I have enough wiggle room to use my 26.4mm bars?

Thanks for whatever information you have.