Personally, I do everything I can to make the partitions different sizes, in case I need to correct some problem, I can tell which one is which.
But since the first two partitions are equal, you want to make the partition on the 2 TB match the 3rd partition on the 500G? Which means you would have to extend the partition to 387.63?
Using a third party partition manager might be your best bet, something like Partition Wizard...