Door jamb perpendicular to frame?

I apologize for asking a stupid question, but on a '29, is the door jamb (front edge) perpendicular to the frame? I have a really shot cowl that has just a little bit of the frame mounting holes left on one side only and I want to know exactly where the fire wall will be when I get a better body. I can email a picture to explain if that would help. Thanks!!



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