The bulkhead bush was fine with no play and no perishing so I left it be. Unfortunately the rubber sleeve for the spring was in less healthy condition and fell apart when I touched it so I'll have to come up with an alternative arrangement there.
I'm not sure about the provenance of the wire locking but from my googling around this issue I've seen plenty of pictures of exactly the same setup (e.g. this one on Chris Witor's site:
https://www.chriswitor.com/proddetail.php?prod=150213SH) so I just presumed it was factory - at least in some markets. You could only lock one set of bolts with wires through the heads as the other two are allen bolts recessed into the bushing so it makes sense just to do them both through the other end.
I know the flexible joint is there to account for the differences in alignment between the two parts of the shaft but from what I've seen online this is quite a lot of flex - it doesn't matter what orientation the wheel is at, it is always flexed to about this amount. I just wondered if I might have missed something which could have caused the two parts of the shaft to be even more misaligned than is normal but with the power steering rack bolted directly to the suspension cross member there's very little scope for movement anywhere in the setup.
I guess I'll just leave it as-is for now but keep a close eye on it. I don't trust modern bonded rubber components to be under this much strain for long periods without splitting or becoming unbonded. Hopefully I'll be pleasantly surprised
