A tale of two headers, one on a 3 and another on a 4A, both pacesetters. First one was a virtual perfect fit with only the slightest leak on one cylinder. The other was, shall we say a challenge. Wound up cutting the flange on a surface grinder at about 10 degrees leaving the top of the flange about an 1/8" thinner at the top. Buuut that cut too much weld. Rewelded, reground, and then it was a perfect fit. Pay your bucks, take your chances. Can't remember if they were the first four into one.
Tom Lains
TS8651 & 58107