The Ghast are a MUST!!!!! I have taken out a CAV with My flight TWICE. What ever you do get as many as you can take. The Assassian is great as well. I see nothing wrong with your list. The one thing I have tried to do with my force is to buy a platoon at a time. You can get 4 CAVs depending on the price, for around $50. This is just My two cents worth.
Interesting. You may have changed my next CAV purchase. A flight of Ghasts+a few tanks for my tank merc company+a Wight and another Specter. Sounds good to me.