I can’t help with how much flow and what intensity it should be at, since that is very dependent on your aquascape. Watching how your corals behave in the flow is helpful.
That 30” is pretty deep to cover with just 2 MP4’s, though. You want flow for the corals but you also don’t want any dead spots that can accumulate detritus. I have a tank that is 24” deep, and just placed a cheap Powerhead aimed for flow behind my rocks to help out. My tank is only 36 long though. You may be better off with a couple.