Assuming its the E5-2697 V2 (2.7ghz 12-core)? If so, that is about as maxed out as you can get that machine (GPUs, RAM, CPU). 64GB of RAM should be plenty (however, you can max the thing out at 128GB). The D700s are as good as it gets with that machine, barring an eGPU. Very nice pickup.
If you bought it used, you probably can't get AppleCare for it. You can go on Apple's website and enter the serial number in to see if there is any AppleCare left on it.
What are your plans for it?