side exit header fab questions

[garym]

I am going to build a set of side exit headers for my top sportsman drag car. I have been buying the mandrei bent 21/2 od 16 ga 304 stainless tubing to build the headers.Motor is a 762 big block chevy with dart billet block and billet CFE heads. Hope to have the engine by march or april so I am getting the tubing and collectors andall of the other parts to build the headers. So I have 308L .035 tig rod a good band saw and belt sander,etc . SO questions I have are:
Tig welder settings I was thinking heat around 50-60 post flow around there is a setting for the size electrode that is being used and I go by that setting welder is a miller syncrowave 250
As far as cup size I have the monster 14 cup with a 3/32 electrode or would a 1/16 electrode be better?
I read where silicone bronze tig rod is used to weld the header tubes to the header flange to help the header tube from cracking . I have priced the header flanges from PRO FAB and they are NOT CHEAP but then to again nothing is cheap nowadays !!
I hope to get some input to help me along on this project. THIS IS A GREAT FORUM!! Thanks gary m.

[turbo camino]

What about purge? That's an expensive bunch of materials to be experimenting on.

[garym]

I have a purge kit just forgot mention that I had a purge kit

[garym]

I also would like to know what length the primary tubes should be? I was thinking about 26 inches but since I do not have the engine it is hard to say
Thanks for the reply.