Building a tubing header for this engine is not easy, but it can be done. My ex-partner cannot weld; he has a pacemaker for his heart (as di I,) and welding is a no-no for us. (I can't weld, anyway; no training nor experience.)
I broadly suggested the parameters for this header, acquired the flanges, tubing (1.625") and collectors and gave them to him. He put them together in the required configuration, by adhesive-taping the pieces together (really!), and took them to a welder. who T.I.G.-welded them together. They are 16-gauge, mild steel. Then we took the finished piece to a plating service in Midland, Arkansas (we are in Little Rock, 140 miles south of Midland,) and had them ceramic-coated, imside and out.
This is what they look like; I think my ex-partner did pretty good job, for a first time effort. I never TOUCHED them...
You can do it...