I saw those metal VC and almost switched on my N55 when the vacuum reservoir failed.

The cam is a whole lot less critical than the crank i think you cold use an old cam in a new cam shell but I've not done before you should just end up with a little tighter tolerance around the "bearing shells" which should help with the oil pressure and lifter tick.

__________________
2011 E70 • N55 (me)
2012 E70 • N63 (wife)