As to the actions, when we rebuild old C Bechsteins, we completely modernize the actions, and save very little from the original actions. The older actions can be made to work well enough, as can Bluthner patent actions, but our approach is that our rebuilds should dramatically out perform their new equivalents, or what is the point.
I have a 1879 Bechstein. I love its sound, but the action is quite heavy for me.How much should one expect to pay for new actions?
As to the plates, we have rebuilt many pre WWI C Bechsteins over the past 30 years, and only a couple had cracked plates. These were pianos that belonged to customers, and they were rebuilt with a clear explanation. The plates were repaired and reinforced, and are holding up wonderfully, and I have no concern about thier longevity.