The only thing I know about the f cam is it was designed in the early stages of 5.0 racing, it's the 3/4 race cam of the 90's.
Think about it, old technology, where something worked 25 years ago because it was the latest technology, technology evolves, your mechanic likely has not evolved, ask him if a duel pattern cam would help you with torque down low and if he says huh? or I don't know then get a new mechanic, or better yet learn for your self.
I did and still am, though I probably had a head start on you.