I'm assuming your headers are the Kustom design. Since mine are the Bill Thomas design, I wonder if your collectors fall closer to the stock pipe location than mine. Once we got a good look we realized even re-bending the head pipe we still would not have a straight shot to the collector. We opted to cut the head pipes back a little further and have Eric G bend us some new pieces which worked-out great. Here's where he's at as of today:

Work of art!!

Paul, I had Douglass style 4-bolt round flanges made some years back if you prefer that style over the 3-bolt style. I have extras.

Thank you, Jon.....appreciate the offer but the collector side flanges are already welded.

This is the first example I’ve seen of collector flanges installed on reproduction 67 Z-28 headers and I’m wondering if this is due to the production date of your car and the availability of the 2nd design Douglass Headers?

I hadn’t considered installing collector flanges on the headers for my 06E car but will now.

Your exhaust installation looks great!

My car didn't get factory headers but it did have first generation Doug's headers the original owner put on shortly after he bought the car. Those headers had collector flanges. Honestly, I wasn't looking to do a true period installation, I just wanted to do a really clean installation that was achievable in 1967. My fab guy wanted to do band clamps on the entire system in the name of serviceability but I didn't want to go that way. Here's a couple shots of the first gen Doug's: