I need to run a direct burial 380 ft. to a 200A subpanel for a single family dwelling. It will derive from a 320A main serice feed. After my calculations with a 5% voltage drop I will be running a 350kcmil AL for the ungrounded conductors. In addition to running a 1/0 AL service ground I will be running reduced 4/0 AL for my neutral feed. Does seem correct?