Don,
Just to chime in and show my ignorance on the subject,(seriously no real practical experience).
According to what I have been told by the old men.
Making headers that actually work!
Require flow testing the way the factory does it.
For example:pipe length and diameter determine flow,
CFM and draw.
Your supposed to chain these in a manner to sequentially release exhaust,to increase vacuum and draw.
I think I would steal a blue print offline for a car with your CFM and CID.
Keep in mind you are reinventing the wheel.
This is why good drag flow headers cost so much.
But it sounds like a blast.
You will be a TIG master by the time your done.
All I have ever done is header repair on collectors, believe or not we used coat hangers for brazing rods.
(carbon steel) they worked OK for a poor boy special.
We could not afford brazing rods.
Mark
