Here is a diagram of the pump housing.
https://ibb.co/k6h85CQQ

Item no. 10 is the sensor that I removed and filled with oil, its on the top of the housing and allows you to fill using gravity as well as pressure from the oil can.
I assumed that would be on the high pressure side of the pump and provide immediate access to the pump volume where the gears are.

The PRV no. 7&8 is on the other side and points down, thus as an access route you are working against gravity. The RVR was assembled and in position. So should stop any oil in the chamber being returned to the sump.

Hope that clarifies the entry for priming.

Thx for all you help