Been a couple weeks, so, here's an update!
On the interior, I installed my seats, carpet, and padding. I also fixed my radio, installed a new antenna, and figured out a speaker box mount.
I also had a new driveshaft built using my existing slip yoke, lengthened ~1.5". It fixed 90% of the vibration problem, but I'm still getting some chattering / vibes from the driveline on decel. Jesse had a spare NP241 mainshaft left over from his SYE conversion, so I installed that hoping it was my splines that were worn. It didn't help at all, so it's looking like my problem is in the slip yoke it's self. Price for a new slip yoke was ~$100 installed and balanced, that was more then I wanted to spend, so I decided to go another route. I'm sick of messing with driveshafts and half-fixes.
I called up Tom Woods, and ordered their NP241 SYE Kit, and a(nother) new driveshaft. This time a 1310 CV shaft made to order based on my measurements with all new parts. To go with the CV shaft, I flipped my 6 degree axle shims around, and my pinion angle seems just about perfectly in line with where the CV will land. at the SYE.
Rush order, 2-day shipping. Should be here Thursday afternoon. Only cost ~9x what the slip yoke would have.
3 Days to Dunefest!
-Rob