Any header made for a 70 Stang with a 351C should fit the 67 also.( engine bays from 67-70 have the same dimensions) FPA's are good but as Mach1Steve said are pricey.
I have a 351C in my 68 coupe and i'm running Hooker LT's. Everything is so tight w/ the motor that I ended up having to make some torque straps to keep to motor from jumping around