Wow! The lightest FD ever made breaks at 40 years after manufacture. Probably from operator error.
Yes, those are 52-42 FDs, 54-42 works fine. Pure, '70s racing FD. As good as there was. But 52-34 was beyond comprehension when that was made. I used that Mk I on my Mooney set up triple when it was new and it wasn't great.
Ben