New... Panerai.com
Used... paneristi.com accessories corner
My wrist size is 15.87cm or 6.25 inches.
If it were a 44mm Luminor, I'd say something close to 110/65. You might want to search the sales section and pick up a couple of cheap used straps of different lengths (but close that length) to see what works best for you.
Measure the strap that's on there now, work out what the ideal size for you is and deduct the excess from the size of the current strap.
The buckle end should place the buckle square in the middle of the back of your wrist or slightly to the tail side and the tail should be long enough to leave a suitable amount to go thru the keepers.
Yup, main this is that it's comfortable in that position.
Both straps are stiffer than f.e. a custom made Gunny strap...
I have a black gen gator 24/22 to sell for deployant. It’s the semimat version black, black thread and black leather in the back (not the older cream one).
Let me know if that could interest you.
Do you have the gen paperwork and certificate