I'm just in the process of doing the exact same thing with my old HD DVD case and stumbled across this thread, your drive looks excellent pal.
I've got a Benq to use in mine and I also ordered a few weeks ago the exact same Sata to Usb mini board as you used and hoped it would work which looks like it does!!
My intention is to do away with the two type A usb ports and just use the mini one (as its only for ripping), that way I'll save space inside and solder it straight to the sata to usb board (think you mentioned that above?).
As you, I'm still getting power from the main board in the HD case so this will also power the fan but I've got a Maximus 360 power unit hanging around that I donít use so I've soldered the power (12v, 5v and grounds) from the main board pin to a molex connector to power this.
My hope (before I read this thread) was not to bother with any eject switch and just use it in Windows but you said that this doesn't work? So my next step was to remove the eject button from the Maximus board and still utilise the original eject switch on the drive by soldering the wires back to the Maximus board and hopefully it will still eject, from the four wires on the eject switch (red, green, black and grey) do you know which is what for power and such?
Also which wires do I use from the mini usb on the HD case as there are 5 wires but on the sata to usb board there's only 4 solder points and obviously one's ground?
Many thanks for your pictures and posts they've been very helpful.