Here is the Gran Sport catalogue page from 1972 (courtesy of Kurt's Headbadge website):
Although the catalogue photo doesn't show it too clearly, it is evident to me that the curvature at the bottom is quite different from the OP's.
Here are the tech specs from the 1972 catalogue. The column for the Gran Sport is near the middle.
The handlebars are identified as "GB Randonneur", one of the hallmarks of the 72-76 Gran Sport.
I'd be interested in reading from the OP, if known, as to whether the handlebar and fork are factory original, or post-factory replacements.