Leeedy brought up a good point in that other thread that if the pump, fluid or other parts of the hydraulics is not original and is a replacement the factory pressure specs may not be accurate. If that is the case you will need to contact the seller of the pump or parts to verify what they want used.
From photos in the SM I would almost bet the port size is 1/8 NPT at the pump as that was a size Packard very often used for various tubing ports but if it is high flow or large item it could be 1/4 or even 3/8. There looks to be adapters used at the lines going into cylinders so the cylinder ports might be one of the larger sizes. I didn't see any sizes mentioned in the parts book to verify my guesses though.
If you have some way of measuring such as a micrometer that will fit the space between the hose fitting and port you might check the OD of the threads on the fittings. The visible outside of thread part going into the port for 1/8 would be fairly close to the .405 dimension listed at D in this chart . 1/4 or 3/8 OD diameter is also mentioned in the chart.