Its really not. I have a vague sense that for boats in 70's/80's that Cals and O'Days are good, hunters and Catalina's not so much. The others I have no clue.
I seriously doubt if you will find any substantial difference in quality between O'day and Catalina that would make any difference 30 to 40 years after the fact.
They were both inshore price point boats. If anything the Catalina no matter how old still has support.