1937 Packard 120 Convertible Coupe Top Dimension

[pint4]

I have a question regarding a top dimension on a 37 Packard Convertible Coupe.  I am looking for the measurement from the package tray to backside bottom of the rear bow taken in the middle.  The person doing my top asked me if I could find someone who might have that dimension.  I contacted a couple of persons I know who have Packard 120 Convertible Coupes and they sent me their dimensions but there is a two inch difference between them.  Hoping I can get 1 or 2 more and go with an average or maybe the most common of the numbers.  Thanks for your help.