Khalid was king at the time, but very sickly (died 1982). Spent most of the time jetting back and forth between the US for heart treatment. Fahd was the true ruler as Crown Prince, Khalid did convince Carter to sell Saudi Arabia the F-15s. Khomeini, after taking power attempted to finance and organize to overthrow Khalid, which in turn the Saudi’s financed Saddam in going to war with Iran. I don’t know what the Saudi’s view of the Shah was, but maybe they opposed him for the sake of continued US patronage.
We are on the same page.
This was triangulation with Persians and Arabs vying for most favored nation in the Gulf area.
At that time, the arabists in both the British and American Foreign Affairs bureaus tilted towrd the Saudi Arabs.
Khomeini, after taking power attempted to finance and organize to overthrow Khalid, which in turn the Saudi’s financed Saddam in going to war with Iran.
This is where the religious rivalry came into play.
There was the subsequent attempted takeover of the Grand Mosque in 1979. At the time it was believed that it was an attempted Shiite overthrow, bi=ut according to this link, the leaderhip of the coup was Sunni Wahbbi: http://www.fsmitha.com/review/trofimov2.html
Much of what was going on is still unclear.