Your LFS should have the overflow kit for the megaflow. My AGA kit was about $50. The larger hole is for the drain, and the smaller is for the return.
I'm assuming that it drains 600gph, so you'll want a pump that will match that once it is pumped back up to the tank. I'm using a mag-7 (700gph) and it works great.
I don't know what other equiptment you're looking for.
-Justin