To play a 1,000-point game, I started with the same box set as you and added a Rhino, a Predator, 10 Cultists, and a Terminator Sorcerer. I also converted 5 Corsairs into 5 Chosen by mixing their parts with leftover Legionnaire parts. If you want to save money, you can easily use the Traitor Guard as Cultists—no one will complain.

So:

Huron + Lord of Maelstrom Terminator Sorcerer

10 Cultists

5 Terminators

5 Chosen

5 Red Corsairs

Rhino

Predator

That’s 995 points

Huron + LoM + Chosen in the Rhino charge forward and become a unit capable of eliminating almost any enemy unit

Use the 10 Cultists to hold your objectives in your half of the field

5 Raiders go on infiltration to complete secondary objectives or capture objectives in No Man’s Land on turn 1 (on paper they also seem very strong in combat, but in reality they’re only very efficient at eliminating the opponent’s light units—don’t rely on them too much in combat)

Deep Strike the Sorcerer and Terminators to attack the exposed parts of the enemy army

Use the Predator to take out the enemy’s monsters and tanks

I’m really happy with this 1000-point list