Frank had a connection in Floyds' state, MD where the majority of the nameplates were manufactured for Chrysler.
As for the 440-6 shaker nameplates having a slight curvature in my opinion that is a myth.
They are going to get that when you tighten them with speednuts to meet the slight curvature of the scoop in that area.
Challenger shaker nameplates are a different story, they do have a taper because of the size, thickness and length.