The Phantom 500 can be installed in the P180, and its ATX12V cable will reach even the nasty "behind the keyboard connector" spot easily.
I'm using an ASUS P5WD2 Premium motherboard, which can take either ATX12V (4 wires) or EPS (8 wires). The Phantom supplies both connectors - it has an 8way connector at the end of a reasonable length cable, then a short extra bit with the 4 way connector on it. I can use the 8 way connector (just) on this motherboard - the cable is not taut, but there's next to no slack. Using the 4way would have given me heaps of slack, but I preferred to use the 8way because it offers more wires, therefore lower current.
Using the Phantom 500 in the P180 is not especially easy, because the Phantom is so long. I wanted to use a 120mm fan in the tunnel so there'd be some air movement past the hard drives, and so the Phantom's fan didn't need to run. I couldn't use the supplied 38mm thick fan, but I found I could substitute a 25mm Tricool (removed from the other P180 I bought earlier).
You have to pull the cables up quite hard to get them to clear the case fan, but once you do, there's a nice clear air flow in the power supply tunnel.
Can't say that I'm thrilled with Antec's Phantom build quality these days - the wires coming out of the Phantom are all tangled together. Looks like they had all the 12V wires together, all the 5V wires togethers, and all the neutrals together, then grabbed them any-old-how to make up the cable runs. The first four to six inches are horribly tangled. Worse still, they aren't all the same length, so if you try to use cable ties to neaten them, you can end up with bulges where some wires (often the yellow, for no apparent reason) are longer than the rest. For the price of the Phantom I'd expect better.
Must say that this made me respect the PC Power and Cooling power supply more!