I'm not a gunsmith but I am an owner of some Weatherby's with their MkV action and I'm not sure if this is exactly the information you're looking for but I'll pass on what I've learned and you can go from there.
Right wrong or indifferent, Weatherby's MkV action is NOT going to be the first choice for a build platform of more gunsmiths than not. In fact, you will probably find a few smiths that won't build on them at all. Now that doesn't mean they are a bad action, just that some don't like to play with them for one reason or the other.
One of the biggest concerns I hear from the gunsmiths I've talked to was they struggle to feel confident all 9 lugs, even after lapping, are/were contacting the same. Other than that, I believe they can be trued pretty much the same as any other action.
IMHO, if you are serious about building on a MkV you should look for a gunsmith that LIKES to build off of this platform. JE Custom and Kevin Cram are two that come to mind and not only are they great supporters of this Forum but I have personally talked to both and both these guys were excellent to deal with.
There are quite a few guys on this forum that have built semi customs around the MkV action with great results.
Autorotate is on this site and he has a couple semi customs built on MkV's. Look him up and he can probably give you much more information than I. He wears a white lab coat and reloads in a vacuum sealed environmentally controlled lab and, wellll, I think he's a little OCDish too but shhhhh, don't tell him because he still thinks he's normal.
None the less he is great to chat with about his MkV builds.