Nice to see the real deal. A while back I was at a car show and parked besides what I assumed was a clone AC Cobra, it was not a clone, guy pulled it from a wrecking yard, it was sitting on top of a three car stack. Those days are long long gone.
I hand ported 69W heads for a 289 back in the day, best time was 12.7s. To get decent compression with those heads I had to use a 12:1 piston to get close to 10:1 and that shrouds the already too small valves. I had much better luck with Iron WindsorSr heads, paint them blue and difficult to tell they aren't stock. Ran low 11's with those heads unported. IMO the factory S2MS intake and tri-Y headers that everyone raves about are over-rated, they are just way too small to make even decent power.
In 1988 I was having a Mustang painted a couple units down from "The Shelby Shop", now Legendary. Beautiful restored 68 GT-350 with factory Paxton, day before customer pickup they decide to have a test drive, throttle got stuck on that Cobra carb hat, and they crashed it (not badly). They were in full panic mode. They do really good work but unaffordable unless you have something really rare.