Building your own headers.

Hi I am going to be building a 14.1 360 magnum stroked to 408 inches. The engine will be going in my 91 Dodge Dakota sport race truck. My problem is 1-5/8 is the biggest size header I can find that is offered for my dakota . I have full length hooker headers on it now. I am wanting to go to a 1-7/8 x3.5 header size. So the point of me making this post is I have never built a set of headers. Thank God my son knows how to tig weld.lol does any body have advice on the ins and outs on building a set ?