So after a lot of searching I found a 6-speed propshaft for sale on autolink.co.uk that was not listed on their site.
For reference , here is a pic of both the 6-speed axle and yoke spline in case there are other people out there going the same route. You want 25 splines and a 38 outer diameter on the yoke. Notice that 2 splines are missing.


New vs old flywheel. It is supposed to be 13 vs. 20 pounds stock.

Getting the pilot bearing out was a b**** and required me to buy a special sliding hammer tool for $$$


Every thing mounted torqued down with locktite.

Based on pain and bad language the 6-speed must be heavier than the 5-speed I replaced. I had to make a "special" tool to balance it on the floor jack. Removing the PPF would make the job easier.

First impressions;
It totally transforms the car. 2-3rd are now much more usable. I am confident that this will better my times on Rudskogen as it will be easier to keep it in the 5500-7200 rpm range out of corners on.
The flywheel does it job by making rev matching easier but could be a couple of pounds lighter for even faster shifting I think. I would totally recommend swapping to a 6-speed. The best thing is of course to get a 2.0 with the 6-speed stock.
The Moss shifter is terrible. Sloppy, noisy, not compatible with my fancy $$$ bronze beat rush shifter bushing, the reverse spring is way to weak and the part of the shifter that is touching the 1-2 guide plate is too small making it hard to shift to 2rd . The throw is also too short making gear changes physically hard an with less precision.
It's crap!