Hello there! And if no one has said it yet, welcome to the forums!
I like a lot of live rock in my tanks, I usually stack the entire back wall all the way up to 6" of the water most of the time. I like the look, and the filtration power of all of the rock. That's usually around 1 1/2 pounds to 2 pound per gallon. A mix of 50% base rock and 50% live rock will save you some money upon start up.
Now a days, these youngsters around here opt for very little live rock, piled up in sections and then they spread coral out around it. Then they have to use oversized skimmers, oversized fuges, and all kinds of chemical filtration media to handle their overloaded underbiologically filtered tanks. But, it's whatever you want to do these days.
For a 75g FOWLR tank, you're right at the minimum flow. Though, if you add more live rock and another Koralia 750gph, you'de be right at where I'de like to be if it was my tank.