SPF GT40 A/C Refrigerant Capacity?

Update: Replaced Receiver/Dryer. Pulled vacuum for two hours. Charged with 32 oz. R 134a. Low pressure = 28 psi, High pressure = ~180 psi. Vent temps still in the 70s, at best.

Haven't been able to locate any filter or orifice tube. If there's anything in the photo above that I can check, please advise.

Question: If you've initially had oil in the compressor and have pulled multiple vacuum cycles, do you need to put more oil into the compressor at some point? If so, when?