Major issues here, I've done research on these and some of this was posted earlier in the thread, but the XFlow 280 from Alphacool is too long to fit in the SM580. Note that its length is 334mm which is longer than the actual case. Second, the Apogee Drive pump height itself isn't the issue, it's the fittings. Even in the Ghost (see JayzTwoCents' video on this), you need to rotate the fittings in such a way that they fit in the case. The Sliger SM cases all have less CPU cooler clearance than the Ghost, therefore its unlikely it will fit, even replacing the pump, unless you can completely change the integrated fittings.
If you go with the XFlow 240mm radiator, it should fit no problem. Note that if you want to fill your radiator from the top, the new NexXxoS v.2 radiators from Alphacool have 6 fittings on the ends of the U, so you could fill from the top, assuming the hole isn't blocked by the case itself. At that point the XFlow becomes redundant (although it should have less restriction on flow rate).