*Bumps an old thread with a great mod*
I tried a version of the bottom bay mod. I also used a drill on the rivets to remove the 'enclosure' (for lack of a better term) that prevented a 120mm fan from being mounted in the bottom, front bay. Then I ran into the same problem as the OP -- the bottom hard drive bay is a few millimeters too wide and runs into a 120mm fan when it is mounted there.
I went to do the 'remount the screws a few millimeters to the right' mod that Bumthology did, but I found that I did not have a small enough drill bit that could eat through the steel of the case. Stumped and annoyed, I threw some two-sided tape on there. It's 2-3mm thick tape, cut very thinly so as to not protrude much, on both the top and bottom guide bracket, to see if that would hold the bay in place well enough. Then I left it in a vice overnight, pressing it down, to see if it would hold.
Turns out, it holds AMAZINGLY well. It was a VERY easy way to do the exact same mod that Bum did without dirtying your hands with a drill (or requiring the equipment to do).
Attachment:
bottombay.png
I also used a rotozip (I don't have a dremel

) to cut a couple holes on the opposite side of the case, behind the middle hard drive bay mounting area so that there will be more spaces to run cables through. Although my tool was crude, I managed to do a mediocre job. I then used a dremel grinding bit in a drill to grind the edges so it is quite smooth.
Attachment:
backside.jpg
Oh, I also removed the bottom middle fan bracket entirely, so that area is free of obstructions. This reduced the amount of support for the area held up by the bracket, but since it doesn't hold any weight (if you're doing it right), I don't think it'll be a problem. I'm curious if, on the P183, the middle level bends in a bit because of the lack of support, or have they reinforced it somehow? Regardless, I don't feel it to be necessary so it's gone!
Next I plan to do an internal paint job on this whole getup. I love seeing all these threads (however old) with all sorts of great modding ideas. Thanks for the inspiration, folks!