I've done this. I also have a '65 Barracuda with a 360 under the hood. It was a total *****. I like power steering so I had to rig up a very expensive aftermarket power steering gear. The clutch linkage z-bar absolutely would not fit despite what the manufacturer claimed, so then I had to go about rigging up a hydraulic clutch assembly which required all sorts of cutting, welding, and fiddling. If you have an automatic then I think you need to have a 904 gearbox. Check with Doug's or TTI to verify that.
I went with Doug's headers and I do like them very much. I was thankful for the slightly smaller tube diameter and slip-fit design as opposed to the larger TTI headers.
It was a ton of work and fabrication that I didn't want to do and I'm not sure if I would do it again. After all the modifications I had to do to squeeze in the headers it cost me an extra $1500 on top of the headers themselves. But the sound is amazing with a pair of Dynomax Super Turbo mufflers.
What's your application? There have been many different incarnations of the W-2 heads, but originated as race heads (high RPM).
I have a 66 with 408 and w2 heads. I bought Hedman fenderwell step tube headers for a 67 and up and w2 flanges to weld on. Have not installed the headers yet but felt like this would be the easiest route.
Is your 360 stock, a little more, or HOT. What are your plans for the car? Fun driver, daily driver, street and strip, or race only? Depending on use, headers may be more grief and $ that are worth it. I hope others with 1st gen Barracudas will add commits.
Mike