I figured it out, and this method I am using does not strictly require destructive removal of parts to decouple.
With the conversion, I decided to remove all the electronics anyway, it is a useless nuisance for my work. I will mount a LED ring light in place instead. A controller board can definitely be tucked within that housing.
I am going to reverse the disassembly to verify its function. If this works, it is unnecessary to enter from the rear element.
Edit:
Here it is, I got in from the front and removed all the ring light stuff. I thought the ring light was plugged in, so I tried pulling and got a handful of glass shards. How do they fix these if the ring light goes bust? A typical user would not be able to perform the repair.
Anyhow, there is a white gear that engages a much larger internal gear which is a part of the "focus ring" with scales on. I simply rotated the gear to close down the aperture fully, and then removed the gear.
Doing so disables the coupling, which allows me to control the aperture using the BR-4 ring. I purchased an expensive ai/ais to Z-mount "PK cine style" adaptor from Kipon/XPimage. This adaptor allows external clickless aperture coupling which will make the lens much easier to use.
Does this affect chipping? I think it still works! The aperture is set to minimum already, a chip should allow my camera to set the appropriate aperture from the body. I do need to get the rear ring chipped first, hopefully I can pay a more experienced member to do this for me, I will mail just the rear mount. I think this conversion is better. Accessing the rear mount requires the removal of some kind of rear element group which may cause dust to enter. For mine, all you have to do is snip all the wires, remove all the electronics and then remove one gear, much less disassembly involved. It is possible to carefully remove all electronics using a soldering iron but I see no value in that tungsten ring flash which requires some stupid bulky dated external box.
I will try and get another to make a video.
Here is the XPimage adaptor being demonstrated:
https://youtube.com/shorts/gL3lPh0woSQ?si=V3PlVz8oJd6JKQeG I took it from their Taobao listing. It should arrive next week.