I like this site best when someone poses a problem, then updates the group on progress/lack thereof on the solution. Here is my update.
My stuffing box nut was down to the last quarter turn and I was hauled out doing a bottom job. I thought I would just repack the stuffing box and the problem would be solved (hopefully).
First, I took the quadrant off. This took 6 hours because it was completely rusted to rudder post. The rust was underneath, and had not been visible when looking down on the quadrant. After escalating force was applied I ended up using a puller tool which I layed across the top of the rudder post and pulled on the non-threaded holes that hold the opposing quadrant section. It was unbelievable how much force this required and the quadrant didn't "pop" like a propeller but rather fought every millimeter of the way. Not a bad idea to spray penetrating oil on this junction as a maintenance routine.
After removing the nut and the old packing material I repacked it with 3 Amel supplied pre-cut rings. The nut would not engage with the threads, despite the material being very well packed down. If I took one ring out, the nut would engage..........barely.
I reached out to this site as well as Alban at Amel Caraibes.......he said 2 rings would "probably be OK".....not a ringing endorsement.......and suggested a rethreading exercise which I only partially understood how to operationalize.
Based on Eric's (Kimberlite) suggestion on this site, I fabricated a "2nd story" onto my stuffing box. This involved taking the plastic nut, protecting it with teflon tape, and then wrapping about 10 mm of it with fiberglass around the threads. This created a kind of washer that was threaded on the inside to fit the nut. This washer ended up being 10 mm tall with walls that were 20 mm thick.......and very strong.
I considered using resin only, which would have allowed me to make a mold for dipping the nut into.......but opted for the messier (but I think stronger) fabrication method of wrapping strips of cloth impregnated resin around it. It was a windy day in the cockpit and there were times during the fabrication phase that I regretted my choice.
Anyway, the dried finished product was far less precise than I had imagined in my head when doing the planning, however I was able to sand it into the perfect shape. The stuffing box nut turned perfectly inside my new "washer". I mounted the washer atop the stuffing box with 5200 and screws and am now able to put 4-5 rings of stuffing in the box. No leaks. Thanks, Eric.
Knowing what I know now about this system and project, I wish there had been a source for the part which I created. This would definitely have been worth buying and having on the boat. The most surprising thing about this whole exercise was the difficulty in removing the quadrant. The boat is a 2004 and the stuffing box had leaked (or better weeped) only twice.......and yet the rudder post and quadrant were seized very tightly, and rusted in a way that was largely invisible to the eye.
Anyway, everything is good now and once again thank you to the 8 folks who responded to my initial posting and helped me get this done.