I'm assuming you mean the FX4. I don't have that filter or a 75g but the fx4 is rated for 700gph. That gives you about 10 turnovers per hour. If it's too much the FX4 can be turned down. If it's too little the 407 can't be turned up. I have a couple of FX6's and like them a lot, but they are different from most canisters with the pump at the bottom.
I have an FX4 and use it with an 150 litre(35 gallon) aquarium(come as a surprise). It's the best filter ive had. I upgraded from a Eheim Pro 4+ 250 which wasn't powerful enough. The FX4 gives high turnover(10x) but not too much. I don't have to turn it down Its ideal. In fact if I fill the filter with too much media the flow rate is not enough. It's possible to turn the outflow inwards so it hits the glass reducing the spread of flow. Having good churn provides good oxygen for your fish especially when medicating. So the FX4 will be fine for your 75. I recommend it for 150-200 litre tanks as well.