AFAIK, the only differences between R134A and R12 systems were the size of the orifice tube. Your not supposed to mix R12 with R134A either, or bad things will happen. So you will want to be sure before charging.
PAG oil is compatible with R134A (and R12 if bottle states double end capped)
Ether oil is R12 compatible only
If the car was manufactured in 94 it should have R134A... Check the bonnet on the upper rad support and see what it says about refrigerant type and oil capacities.
Also look for any paperwork tied to either the high or low side charge ports... if the ac system has been serviced their should be a report on what was done and when; unless they didn't bother filling one out.