[AzDon]

The factory air (IMO) is WAY better than Vintage Air . They usta say that all the rubber o-rings needed to be changed for 134, but it didnt really turn out to be true. The newer o-rings are green and are available at any part store along with the special o-ring lube. The original pressure shut-off switch is only for low pressure and must be replaced with a high/low shutoff. It also must be in the high pressure line (small line between the condensor and the evaporator box.
Where this line connects to the evaporator, there is a plastic filter/sprayer called the orifice tube installed into the fitting. When you take the line off, you'll see the flat tab that you grab with needle nose pliers and carefully remove and replace. It has o-rings around it and may require a 1/4 turn to remove. This is the item that the liquid freon sprays through to create the misting effect in the evaporator that produces the cold.
Yout leak is probably right at the compressor clutch. It will be sticky around the perimeter and there will be a stripe of dirty oily freon on both fenderwells and the bottom of the hood from the pulley slinging what's leaking.
Good luck!