Seriously, I have a lot of confidence in how it'll turn out. But if all does not go well... - Some of the best threads I've read include the bad with the good. I like the fact that win or lose you're going to give the header build a shot. It seems like a daunting task to me.
I've watched a custom set being fabbed for one of my friend's '65 Coronet drag car but the builder had his own tubing bender. Whenever something didn't fit right he'd swear a lot and throw the tube across his shop. You didn't want to be in the way. Eventually he had each tube formed and didn't have to seam it anywhere. The only welds were to the flange and collector.