After 30+ years (give or take..) you are purchasing a combination
of (A) initial build quality and (B) continuous upgrades and preventative maintenance.
If "A" is too low, it's hard for "B" to compensate for it... kinda like gold plating a t_rd.
Many boats will be, on your best day shopping, about a 50-50 split between A and B.
An old ODay was originally never equal to a Tartan, CS, Ericson, or similar, but it was above some other low end hulls. It's price reflected that, then and likely now, too.
The advice on this site about how to assess a used boat will serve you well.
Before you release your earnest money, though, always get a survey. A good survey will introduce you to many facets of boat ownership -- some familiar to you and some new or unexpected.