Well, adding some Big Bugs is a very good idea.

My personal favorites are Mawloc, and Tyrannofex.
Mawlocs are universally well regarded, so grab one of those for sure. If you can magnetise you can have both a Mawloc, and a Trygon.
A "Dakkafex, or two are also very good choices. If you add a Mawloc, and a Dakkafex, you should have some points left over for other purchases. A Warrior Brood will also almost always prove usefull as well. That all should put you at or near 1000, then just trim or add to ballence.
Good luck! And welcome to the Hive Mind!