R-12 is what it came from the factory with. Take your car to a parts store and ask a counter man to look and see if it has been retrofitted to the newer R-134A type freon, if so DIY freon kit is all you need! If it has not been switched, no big deal to do that either. If you need more help post results of what you find out and someone will help. Youtube is a great source for instructional video!! Just type in what you want to do! Retro fit A/C system/Charge A/C system etc. Both can easily be done, if your son is a little car savvy. There is no need to change a bunch of parts on this car! Just go to youtube and search for the video.
The freon type should be on a lable somewhere under the hood, but I beleive it takes R19 that is no longer produced for pollution reasons, If it is R19 it will need to be converted to R134a refrigerant witch could be expensive..If yor not sure then I would advise to take it to a shop and have a professional look at it. NOTE:it may or may not already be R134a Dont remember what year they stopped using R19..