Those have French threading. You should be able to verify this with a digital caliper and thread gauge. The most common threading is 9/16" x 20 tpi, which is a tiny bit bigger in diameter with a tiny bit wider thread pitch. I wouldn't think you'd have much problem finding a pair of French thread pedals but maybe so if you demand vintage correct. You can always re-tap the crank threads to fit 9/16" x 20 tpi pedals. Many of us have done this with complete success. Steel cranks will put up a bit more challenge than aluminum so use plenty of cutting oil. Whenever I use a pedal tap on a crank, I always insert it into the inside of the crank to ensure clean threads on the outer side. Also make sure you use the correct tap for the side you're doing. Left side pedals have reverse threading,