well first of all with a sps tank DONT count the return pump as FLOW, cause with head heights crud/calcium build-up and pipe slime the flow from a return can slow down to a trickle pretty fast, and your return pump should be just that a RETURN pump and just be used for a means to transfer water to and from your sump........
.....so just count power heads closed loops, waveboxes etc, so as of right now you have a 120 with 300gph which is 25 times turnover in your tank, and i have a 37gallon with a vortech Mp40 that runs at about 85-90%, so i have 75 times my tank turnover.......
.......IME almost all sps can be acclimated to high flow, and actually they will be much healthier as every time they stress and release a slimy mucus the flow helps the coral shed it faster, and keep it in the water colum, and eventually the filter sock and skimmer, and from sticking to another coral