I’ve been riding an ‘88 criterium with a steel fork for decades. It is a great bike, and it is dropout width limited, but I haven’t be able to replace it. Maybe someday... I have always wanted a titanium frame.
I never warmed up to the Series 2.8 or 3.0 with the cantilever rear dropouts. Regardless of the marketing, I’ve always understood it to be a fallout of the Klein lawsuit on the seat stays. Obviously Cannondale dropped them as soon as they had the legal opportunity and never looked back.
If I were going for an older Cannondale, I wouldn’t go any further back than a 1997.
John