Odd thing is, the Alfa has a similar setup and the lower fork bolts on those are notorious for the same issue....but mine was no bother at all. When the time comes, I reckon the only way will be to cut the bolt and scrap the lower WB. It'll be due for bushes by then anyway I guess, so no great loss. No doubt finding the bolt will be tricky.
Proshaft UJ is staked in so don't know how to go about dealing with that. Changed more than a few circlip types in years gone by but never a staked one. Maybe find a local place that can do them?
Bushes came out OK with the method you suggest. The middle of the top one almost fell out, so that was easy, I used the BJ press tool to push the middles out of the other two and after a wee bit of carefull sawing & a bash, the outer sleeves came out easy enough. New ones went in easy with the press tool.
Putting the whole WB, upright & driveshaft lump back in was, er, challenging.
Final kick in the nads was the transmission cooler lines. The set of special tools I bought for the job about 3 years ago....didn't fit and TBH, I don't think even with the right tool it would have been possible without dropping the cats off to give clearance. Gave up on that one - its been weeping oil from the flexi sections since I bought it - it can carry on for a bit. Knowing me, I'll sell it with the replacement lines still in the packet they came in.
Still, all back together and feels fine so just need to check/set the tracking and job done until next time. I did at least have the wit to free off the track rod ends while I was under there....
