If you are looking in terms of what they were designed for, then yes, they are excellent heads. They are designed for a street car to make good streetable power. They were built with reliability in mind, as are most Ford Racing parts.
Now if you are comparing them to other heads out there, say Edlebrock, Trick Flow, or AFR, that is kind of apples to oranges. They were really designed with different things in mind. But for the sake of comparison, they will not make as much power as the others mentioned. When the agenda is the most HP, these heads will become a restriction. They can be ported, but if you are buying new, you might as well get a better flowing head right out of the box. Price wise you can get Edlebrock or Trick Flow for close to the same $$$.
What is your goal with your combo?