One thing to watch out for is that Ork vehicles are all open topped and with the changes to 'ere we go and Waagh, they have a nasty threat range. Destroying vehicles will be useful; however, it also means that you will be within range of getting charged by them the next turn (the exception to this is the Ravager since it has the range to stay away).
Because of this, I would focus your Reavers on melee only. With 3 cluster caltrops, you can easily take out any battlewagon or trukk; however, the boyz inside will then get you. Destroy vehicles with scourge and other options and then use the Reavers to assault the unit that was inside.
That said - one of the things that Orks HATE is Fear. The new Mob Rule only applies to Pinning and Morale tests - so any instances where Fear plays out will be useful.
Lastly - if your opponent has MegaNobz, destroy the transport and then try to ignore them. They are slow and purposeful so you can easily stay away from them; however, if you DO want to take them down, use the Ravager. AP2 S8 will double them out quickly. In melee, they will eat through just about anything in your list.