Considering the Army there are ALOT of Anti-Infantry things so any Tank/Vehicle will be a pain. So these are your opponents Vehicles/Tanks:
1. Killa Kans x3
I know there are only 3 but there are 8 Meganobz in Mega Armour, so this is giving then a 2+ save, and that can hurt. A MM can take it out AP1. His things that can take out the Killa Kans and Meganobz(Easily)
1.Dreadnought can in CC but would be better with two of them
2.Devastator squads can but another Dreadnought with TL Lascannons is pretty nice.
3.Termies can in assault but they're good anyway, you can go wrong with them.
4.Tactical Marines CAN but your opponent may just target them and with a good round of shooting will decimate them or in CC
You said you normally plays these orks with this army. But if you start playing someone with 2 Land Raiders or something then you're stuck as they will crush you. You have alot of Anti Infantry and that's good, but you're ork opponent doesn't have too many 11 and then Meganobs, Deffkoptas and Attack Bikes. I think you should make two armies one with Anti Infantry for someone like this and then one with some more Anti Tank if you play a game with someone who has loads of Tanks. The good thing about anti tank is that they can also take out infantry where as anti infantry can't take out tanks with ease.
E.g
Razorback-TL Lascannons, TL Plasma Gun
vs
10 Ork Nobz
3 dead and likely this wont be the only thing shooting them or assaulting them.
5 man Scout squad-Snipers and Heavy Bolter
vs
Killa Kans
At BEST a glancing hit which can Immobilize, and then wreak, but it is unlikely that you will get two 6's and waste a couple rounds of shooting, when think of this.
5 man Scout squad-Snipers and Heavy Bolter
vs
10 Ork Nobz
7 dead. combined with the Razorback that squad is gone meaning he lost his only objective scoring unit or you get 1 KP.
Hope this helped