OK, donor arm was a straight Numark, the SME socket is just held in with a single screw and it was cheap, ~$20 back then.
Tape is where I made the first cut
Here's what the stock wires look like, I re-wired it with Cardas wire and that was far and away the hardest part. The wires have to pass through a tiny hole in the arm right at the pivot point, making that curve without damaging the arm or wires and getting it all back together was a chore. I think I remember having to drill out a little plastic bushing to a slightly larger size where the wires exit the bottom of the arm, even the tiny Cardas wires are a lot bigger than the bare coated wires in the arm.
Here's the first cut location - too long, no chance of hitting the geometry
Final location. It's very close to not working. The SME socket has to be engaged to clear the rest, and it's very close to the first bend in the arm. I used JB Weld to glue the socket into the tonearm - it was a little loose so I wrapped a single layer of that shiny aluminum HVAC duct tape (not old gray "duct tape") around the socket stub before gluing it in.
All together
I got rid of the Empire 5 connector plug and installed RCA jacks, I made this little cover and installed the jacks in it.
I put that where the power cable was located, put a new IEC socket on the far side and also moved a power choke (little gold object now seen just under the new power socket) to the other side to try to get the power away from the signal side
That's about it. It was quite an undertaking, especially those new wires. I would just make sure you are absolutely committed to potentially ruining the tonearm if something goes wrong. But I had a really nice example of a 698 that was toast without a headshell, the cuing and lights all operate perfectly and I didn't see keeping that if I had to replace the entire arm. Plus with the cover, I wasn't sure I could get another arm under there and still keep the cover - I was committed to making it work and was lucky enough to pull it off. At no point in the conversion was I 100% certain it'd be successful until I was done.