Headers tube diameter.

Guys,

I am kind of debating what should be the size of my headers, either 1 5/8" or 1 7/8"

My engine should be making around 500 to 600 HP.
Is a small block 410.

What should be the size of the headers???? I need to huse hugged headers in my car do to clearences issues, but all hugged headers I have found are 1 5/8"....