Sounds like it will look fantastic! What color cables are you going with? I got the white ones and they are very nice, and the sleeving has a very tight weave so you can't see anything through it (I tried but even under direct light, I couldn't see the cables), and is done "heatshrink free" which gives it a very clean look, especially as the sleeving is noticeably slimmer (diameter) than 550 Paracord so it has a very sleek look to it. The best part, to me, is that the material itself is actually extremely similar to Paracord in looks/feel, with a matte fabric finish instead of shiny plastic look. I prefer the look of Paracord sleeving over the rest of the types, so the Bitfenix Alchemy were perfect for me as I don't have the time (or skills) to sleeve my entire PSU. I may try someday, but it will not be any time soon, though I am going to be ordering some white Paracord to sleeve my fans and my 2nd pump (was practically given a BNIB MCP35X, and I already sleeved the first with black Paracord so I would rather not have to redo it, though that one's wires shouldn't be visible at all). I had a 100' bundle from a prior job and it's whatever manufacturer's 550 cord was being used by the military in 2005/6, and I have used a few feet to sleeve the pump, and I will use the rest on all the cables that I want to be "not visible" but may be slightly so. The heatshrink I have absolutely sucks though, so I am going to be ordering a few hundred 15mm precut 1/4" 3:1 Bitfenix Alchemy heatshrink.
I have been trying to figure out an easy, clean way to cover up your bottom cables and I was thinking that you could possibly make a PSU cover out of ModMesh that covers the entire PSU so that it has a much more "natural line" and doesn't immediately appear to be an attempt to hide cables.
Also, before I forget, can you mount the PSU with the fan facing down? (is there a vent underneath the PSU that could allow the fan to pull air through?) If so, I would recommend doing just that, as the cable bundle will be against the back wall not right up front, and the difference can be big visually. If there isn't a pre-existing fan grill to allow this, all it would take is a dremel or a hole saw, a bit of window/fan rubber edging, and a filter that you can simply attach to the bottom outside of the case.
Then, depending on how you want everything to look, you could make a PSU cover out of the Hex Mesh or whichever shape holes you prefer, paint the exterior side black and possibly the interior side the "accent" color of your build, which currently appears to be, well, black lol. I would do whatever color you choose for your cables (please don't do black or red), and then maybe even use a few drops of Mayhems dye that matches that color.
The PSU cover could extend from the rear of the case to the drive bays, essentially giving you a "shelf" that would have a good visual impact on your build.
I am not the best person for this kind of project, not by a long shot, I am just trying to help inspire some ideas
I really look forward to hearing, and seeing, what you come up with.