Tru,
That is hard to answer as only you know what you are going to be doing with the car. As Ford only made the 406 in 1962 and 1963, they are hard to find out here, but many of the other parts from other FE engines can be used. The only 406 that I am aware of around here belongs to a friend of mine and it is a 390 built to 406. The 406 tri power motor was a good performing engine but very rare to find around here any more and expensive if you do find one.
Ron
