I wouldn't do that cutting if I were you... made all the metal bent/dent here and there. Even my tiny little saw does better and I bet it's 100% cheaper than ur mighty cutter.

Btw, how did you mount the two fans at the front? Only double sided tapes? At least try to find somewhere where you can secure it properly.
Maybe you can still place the hdd back into the hdd rack. Push it a little bit forward. If you say that those hdd will block air flow, it seriously wont affect much. Better than crossing cables dangerous hanging hdds.

I should wish you good luck in your mod.

I have one casing, exactly the same as yours.
Time to be butchered.

As in "100% sure" cheaper.

TS, if you want something special, and you have some spare HDD which no one wants, can probably experiment by cutting a window on the HDD. Then ppl will notice the HDD more than the cable ties.