Pedal threads too big for crank? I have a 70's bike with Shimano 600 arabesque components and just bought a pair of Shimano PD-M324. The threads on the new pedals seem to be just a tiny bit too big for the crank arm. I find this weird since (based on some quick research on Google and YouTube) there seems to be just one size for all pedal and crank arm threads, except for small kids bikes.

I'm wondering if anybody else has successfully mounted these pedals on a similar crank arm? Could the pedals be defective?

I can still put the old pedals back on so I don't think the threads on the crank arm are damaged.
Any advice would be great!
You have the version of those cranks that came with French pedal threads (M14x1.25).

I believe there's enough material to tap them to standard 9/16x20. The difference in diameter is very slight. It's important and not trivial to get the tap going in square.