I have solved the rear driveshaft angle challenge, and the solution was actually presented to me when I discovered that the rear engine mounts were shot.
Those rear rubber mounts actually measured the exact 3/4 inch thickness that the drivetrain needed to be tilted in order for the TCase output shaft angle to match the new 6 degree angle on the rear pinion.
So, I yanked the rear rubber mounts out altogether and went with solid engine to frame mounts in the rear.
Doing so meant that I needed some 7/8 inch diameter bolts to fit the existing holes in the engine and frame brackets - Almost $20 for two bolts, 2 washers, and 2 lock nuts.... ouch.
And then I needed a way to tighten down these gorilla sized bolts- Anyone who has ever tried to get a wrench on the factory 3/4 inch bolt heads knows how tight it is in there.... well, try getting a 1-1/8 inch wrench or socket in there... not possible.
so my solution was to drill some 1- 1/4 inch holes through the crossmember from the bottom
which unleashed a natural mudslide of debris - I dug around in there carving all the mud out for 20 minutes per side
Another benefit of these holes is that they will be able to be used to flush the mud out of the crossmember and prevent it from rusting out. Here is the mud that came out from just ONE side... NASTY
But once the holes were done, my 1-1/8 inch socket fit right up in there like a charm
Here's a shot of the passenger side all torqued down to 125 ft-lbs
The resulting angle tilted the engine back a little bit in the bay, but it still has close to 2 inches of clearance to the firewall- Up front, the stock engine mounts are still in place, so I expect no interference between the fan and the shroud or the radiator
Now for the important measurements- I already knew the rear pinion was just over 6 degrees
and when I measured the reference angle on the transfer case (which was 3 degrees stock).... Success !!!
so, I hooked up the rear driveshaft and crossed my fingers that it would be close to 12.10 degrees, and it was damn close enough for me...
So YAY - I now have a lifted, rear wheel drive Patrol that should be able to roll down the road without vibrating the fillings out of my teeth.
The bad news is that dropping the TCase 3/4 inch means there is no way the stock front driveshaft can be used unless I do MAJOR surgery to the crossmember, but that is just another opportunity for another day... I'll fgure out something.