Find the power supply you want to buy on the website of the store you want to buy it from, see if the store has dimensions posted; if not, go to PSU's manufacturer's website and see if they have dimensions for that model; if they do measure the part of the case where PSU should be placed and compare that measurements to ones on the website.
iw ould go with a different psu because that case only supports top mounted psu and a 1000w xfx is rather heavy. from looking at it the only support i see is a small lip and 4 screw holes to hold it in place.