R-12 has been illegal for some time now. Also, AC techs with the correct recovery and refill equipment have let the equipment go since there's no business for it. If you find someone who says they can charge your system beware of what they might put in.

If you plan to keep the car, I would suggest having it professionally converted to R-134. You probably won't notice the slight loss of efficiency in your climate (Boston).

Good luck.