I have a picture of the stainless headers here somewhere on the continuation Mark IV GT40s that were at VIR SAAC convention.
The color variation I saw now that you mention it must be oxidation. Looked a little like someone was polishing out their ss kitchen sink with SOS pads?
I had my 180s coated by Connecticut Coatings. They have their own blend of color which they say is their exclusive color. The coat fully inside and out, then polish them. They look a lot like a mill finish stainless. The color dosen't change.
The exit for the mufflers is in the stock Pantera location like the G4's were. Mufflers are polished 3" core full stainless bullet packs. Saves me a lot of time in reinventing the wheel.
They did the Hooker Comps on my 68 GT350 and when I find a set of headers that fit the 67 GT500, will go that route with them also.
My knowledge of stainless tubing is limited to 409 and 304. Afterall this is the NYC area and it is a veritable technology waisteland. You can't find anything here. Everything I need comes from the Midwest.
The only thing we have here is welfare, bankers and wall street tycoons. It isn't even children and women first, it's everyone for themselves from the start?
No one here knows WTF I'm talking about at all. Might as well be from Mars. Personally I'm from Zluto...but that's another story altogether?
Good luck on the Pantera. Looks fantastic. Hope you finish it someday? LOL!