Also worth adding that you could sell the hacked 360 pad with that imp board and recoup some of your losses.
The downside of that option would be that you wouldn’t be able to use your pass through without doing some modification to the cable or adding a cable- nothing tough, but it might be intimidating to someone unfamiliar with stick mods and wiring. If you wanted to keep the RJ45 pass through, you could solder a 1’ cat5 cable to the USB pins (following the correct cat5 configuration for ground, voltage, data+, and data-, of course) and leave the included cable out altogether (which will likely be way too long to fit in the case, unless you’ve got plenty of vertical clearance). If you can make the included cable fit inside, you would need to swap the pass through for a USB jack.
All this said, replacing the Cthulhu is obviously also an option. You could do a “fresh install” and keep it solderless (would also require a USB pass through). Personally, I would use the ZD in this case, as it’s cheaper and comes with all the wiring (not to mention as easy as it gets to install for someone new).