First of all, please don't use A1200FDfix.lha from Aminet anymore. It's a straightforward hack I did 8 years ago, and while it works, it isn't a very elegant solution...
Very nice pictures btw!
Your first photo shows the correct modification needed on the motherboard. You can already use "real" Amiga disk drives after having changed the copper wire.
But now for the Panasonic disk drive: The stepper motor cable as shown on pic #2 can be unplugged quite easily. For being able to reach the two head cables, you have to remove the cover of your drive (it's hold by 2 screws iirc). Now you can also unplug the head cables without much hassle...
Please don't cut or remove the white ribbon cable as shown on pic #4! You'll need a new drive if you do so.
Just carefully lift the PCB, so you can reach R52/53 and the 34 pin connector CN1.
Now for the fun part: There's a conductive strip at position R53 (marked white between the two solder points) that has to be cut using a sharp knife (you should check the successful removal with a continuity tester afterwards). Then use a small wire and solder it at position R52. Solder another wire from R53 to pin 2 of the 34 pin connector and reassemble your disk drive.
That's it!
You'll have a 100% compatible A1200 now!