I have a set in good condition. They are currently on a car I purchased and I will be removing them shortly. Long story short, in July of 1964 a gentleman in California purchased a new D-Code 1964.5 Mustang. That same week, he went to the dealership and purchased a set of Hi-Po manifolds and then installed a dual exhaust system. A Shelby aluminum intake came a short time later, but otherwise the car is stock. The car has been kept is fantastic original condition over the years and today features only 25,986 original miles on it. After much debate, I have decided to un-do the original owners mods and put the car back to showroom stock. I was able to get the brand new / original exhaust manifolds with the car so I will be reinstalling those. I'll sell the original, over the counter Ford Hi-Po exhaust manifolds for $400. I understand that repops can be had for about a hundred bucks less.
The lifelong project:
1967 390 GTA Coupe
Ongoing rotation of Mustangs to hold me over until this car is done.