AC compressor help

I picked up a used compressor locally from a corral member and have a couple questions about adding the refrigerant oil. The service manual I have bases the amount of oil to add to the new compressor on how much was drained from the old one. Is this a good guideline or is there a ballpark number of ounces I should add to be safe? The manual also doesn't specify where I should add the oil to the compressor being installed. Is there a difference in which hole I use? (like adding oil to the suction side is a big nono, or something).

Thanks

Sounds good, and that makes sense on the high side. Thanks for the clarification.