I can’t help with the “normal” bush diameter, but I can tell you that the AVO design will inevitably and repeatedly fail due to insufficient area to spread the load and too much rotational movement in this application. It rapidly shreds the bushes.
I gave up after 4 bush replacements in about 20k miles, by which time the dampers themselves were shot anyway.
Best path IMO is to bin them and fit something decent. However, if the dampers themselves are still good you could convert to a rose joint (one of the reasons the original bush design is so compromised is that the lower ring is also machined to take a rose joint) or perhaps hunt down a metal cased bush which is a moderate interference fit in the lower ring.
Nick