Adjustable lowering blocks

What size tire are you trying to run? If you used those lowering blocks, would you then just notch re re-drill the lower shock mount plate?

How far can you push in the trans yoke? If you were able to push it in far enough to easily install the rear u-joint, I'd bet the trans yoke is a non-issue.

I have a 325/50/15. They clear (although I have never driven the car) but could use a 1/2" backward movement to center in wheel arch. I have seen the thread where guys are putting in a shim in front of the forward spring perch and running sliders. Mine is mini tubbed and the front of the spring is captured in the pocket that you weld into the frame for a mini tub mod. I also have sliders. I like the car lower in the back, right now I have 2" aluminum blocks. I havent checked how much forward into the trans the yolk will go, but I think you are right in that its probably a non issue.