Virgil:
What you outlined is used for large resi around here. It's a 400 @ 80%. Commercial is usually all calc as continuous load....but that should be the call of your POCO.
If you need a main disco then it has to be a 400.
How about you do this:
Meter pan to a troff; parallel 3/0 & tie the ends together.
Get two 200 amp main CB panels.
Tap 1 set of 3/0 to each panel from troff.
The above is based on your panels being back-to-back with the meter, otherwise you need the disco at point of entry.
If the 320 meter base is unavailable....
Service into troff, either parallel 3/0 or 500 MCM
Tap 3/0 to each meter base (200 single meter)
Run to your panels.
John
