what size neutral in tap

[darcy racing]

I have 350 amp main disconnect on my building and come into a raceway with 350 kcm wire all 3
I am want to making a tap to a 200 amps main panel and think 3/0 for the lines.
Can I use 1/0 neutral and # 4 ground.
I have looked everything i can so any advice would helpful.

 

[tom baker]

We are unable to assist DIYers per forum rules. An electrical contractor can easily assist you with your application.