Is that sure that revolution could still happen if Kingdom of Iraq would be still around?
Most gulf monarchies were still there. The shah was on particularly shaky ground because many Iranians disliked a regime put in place by a CIA backed coup in '53.
Or that there would be war?
The shatt al-arab problem and others could lead to it.
But if so, probably Iraq would get massive US support.
I dunnoo...as an arab country, it opposed Israel in '48 and like the Jordanian monarchy, probably would've continued to oppose Israel, albeit mostly with British and French weapons instead of Soviet. There is a limit to what the US would've sold them. The US supported Iran down to '79 in the OTL. Iran would likely be better armed than Iraq. The latter wouldn't have its big Soviet arsenal of the OTL and there was a limit to the quantities available from european suppliers.
I think Iraq would've fared even worse against Iran than it did under Saddam.