Turbo tube diameter

[Crosley]

What tube diameter to use on a turbo manifold for a 250 engine?

1.5 inch or 1 5/8 diameter at the exhaust port on the head ?

8)

 

[Does10s]

I'm using 1 5/8" if that helps.
It's the closest to the port size for the flange. And if you get the aluminum head then it'll be that much better!
Will