I used a 144 pcd Campag Grand Sport 52 as a middle on a 52-36 double , but
... no shift ramps or overshift pin to go behind the crank arm, They're

symmetrical other than the counter bore shoulder to let the chain ring bolt settle in, more flush

now , like a Stainless Surly will flip over and wear 2X as long.. chainring bolt shoulder just sits outside the flat piece of steel.

I'm fine friction shifting all sorts of non pinned and ramped chain rings., you use the overshift ,and recenter the FD cage over the chain, Skill,

I've used for well over 40 years. JFK was Breathing normally, back then.