It looks like you have an SFX power supply listed, and from what I'm seeing that case can use a regular ATX size one. Unless there's a requirement I'm not noticing, you could spend about half as much and get a pretty much equivalent ATX unit, especially if you drop down to 80+ gold from platinum - you probably won't notice a huge difference unless electricity is extremely expensive where you live.

Personally, I too would look at air coolers instead of an AIO - for the price difference on those two parts you're starting to get close to doing an older used GPU now instead of later. Asus says 130mm clearance which isn't enough for to the biggest of tower coolers, but more than enough space for air without any real thermal compromise - especially on AMD. If you have the stock cooler that came with the APU it's at least worth trying before spending a bunch, you might be surprised - the AMD coolers are pretty ok right now.