Yes, the older 27's are quite different.
I also have an older 27, a 1977 model, and they do differ from the newer ones in a couple of significant ways. A very significant one is the cockpit layout. Our older models were designed for tiller steering, so the cockpit seats go all the way from companion way to stern, whereas the newer models don't. They are designed for wheel steering, so the seats only go part-way back, leaving footroom for stepping around the pedistal and wheel. Other differences include whether the head is designed for a shower, the design of the dining table, the design of portlights, etc.If I were to add wheel steering to mine, it would not be pedistal type, because of the lack of being able to step around it in the cockpit, not to mention that the floor of the cockpit would need to be strengthened quite a bit to withstand the stresses of pedistal steering. Instead, I would probably go with a "traditional" system, such as an Edson rack and pinion system, or some such thing that doesn't use a pedistal, but just replaces your tiller with the rack and pinion and a wheel. But that can cost several boat bucks, so I'm sticking with the ol' tiller for the foreseeable future.