Mark
In your first contact with Tech guys (Joe Timney), provide if you can, exactly the similarities between the two displacements.
I know some of them, but not having built a 250, cant be specific. I thought, (perhaps wrongly) that the block castings were the same. The engine design community viewed that engine as a stroked 200. I think the engines were produced on the same machining and assembly lines at Lima Engine Plant although that was a little before my time as I started with Ford in 69.
Do provide lots of dimensions, pictures, production figures and availability.
With respect to the crossflow head, that may be an entirely different deal since the base engine design was u flow with that silly intregal intake manifold. (talk about cost and complexity reduction).
Good luck
Rick