What power supply did you try to get? It takes most normal PS/2 form factor PSUs(often referred to as ATX but thats the electrical spec, PS/2 is the physical), the case has plenty of space to permit a long PSU like an HX1000 so the only problems i see that you might have run into is that you might have gotten one of the large CPX form factor ones that are antec specific, or one of the weird form factor PSUs for low profile machines.
If you just need a good PSU to fit in there, the Seasonic M12II 520 W should be able to handle any single GPU system. It is also currently a bit cheaper than the non modular S12II 520http://www.newegg.com/Product/Product.aspx?Item=N82E16817151093
Edit: typed wayyyyy too slow, that PSU looks like it should fit in your case, did you try flipping it over so the fan points into the case? That should lead to all the screw holes lining up.