I'd strongly suggest completing the requirements for a Decurion.
From there, you've got a Canoptek Harvest formation, and you're a Doomsday Cannon away from an Annihilation formation.
You can fit that quite nicely, inside 1500 points, with a handful of points to spare, to bulk out units or dork about with other things.
The critical element, would be to find a way to get Ignores Cover. I can't think of anything that Necrons have that can do that, other than close combat. So an idea would be to enjoy the Relentless nature of your infantry, and attempt to close the distance and engage in assault. You're tough enough and cheap enough [model wise] to outpace damage production. It will also help to keep you from being mauled by Plasma.