Hi There and welcome to Chevy Chatter!
Rod shop said it came in that way. I disagree.....
The rod shop is correct....the rumble lid on a 1930 Chevy Sport Coupe overlaps the rear quarter panels...the lid is not flush with the quarter panels.
What you are referring to as a "front cowl" is actually the panel that goes between the rumble lid and the rear of the roof panel. That panel is called the "deck lid upper panel". The panel below the rumble lid is called the "deck lid lower panel".
Good luck with your project.