Good luck with that. You will not find a foundry here in the states willing to do it for you at a reasonable price. Reasonable price, demands you order a crazy amount of castings. How many small block Mopar heads you going to sell? Guys complain to high heaven if the head is a nickel higher than someone elses, so US foundry is out of the question.

Edelbrock can do it, because they OWN their foundry