Currently assuming the pump has two impellers, one for PAS and the other for the SLS system. However my assumption is that if the SLS side runs dry it will eventually cause the entire unit to seize.
More investigation is in order. I am sure I read a TB from Jaguar about the removal of the SLS system so I need to find that again.
Update - So I have not been able to find the retrofit guide yet, but it does look like there are various generations of SLS with the later cars 93.25 onwards having separate pumps in the same housing.
1993 (94-MY) XJ81 VIN - 67xxxx
Salt Lake City, Utah.