If you have the system dissassembled, first thing to do is put a conversion kit for R134a. I would also get a new accumulator so you have fresh desiccant.
Once it is all together, you need to vacuum the system for 30 minutes to an hour to make sure there are no leaks and remove all moisture. From that point, you charge it with R134a, and PAG oil. That should be it.
You won't find R12, and if you do you can tell the price difference. R12 is ~$80-$100 a pound, vs. $10-$15 a pound for R134a. Make sure that it says "automotive" and R134a somewhere on the label, there are lots of knockoffs on the market and some can be flammable.
PAG oil is used for R134a systems vs. Mineral Oil in R12 systems. You probably won't find it either, so no need to worry about that.
As for specific amounts of refridgerant and oil, some of the others will have to help you out, or find an AC shop to help you charge and lube the system.
Also, how is your orifice tube? Its worth replacing as well, they are just a few bucks.
[This message has been edited by BlackEmrald (edited 08-07-2013).]