On my 1977 standard, I use Ohlins 36E type shocks made for Triumph Bonneville (the new Hincley Bonnie) I believe these are 342 mm C-C (almost 13 1/2 ")
I have not actually ridden the bike yet, but at least it looks fine. This length is in the recommended range for the XS anyway, if you are looking for better handling and more ground clearance. These are not 100% bolt on, as you will need a sleeve for the bottom bolt, but that is not much of a hassle. The top mount fits as is.
A definite advantage of these shocks is that they have a 100 mm stroke, which will give approx. 120 mm travel at the wheel. Other, stock length shock mostly have an 80 mm stroke, giving less than 100 mm travel at the wheel. I tried Hagons for half a summer on my bike, and they did not impress me at all...They look "classic" but are functionally poor.
My advice is that if you want your cafe to handle good, not only look good, is to get some modern shocks from WP, Ohlins, Wilbers or similar vendors.
Most of the time you get what you pay for, and that is definitely the case with suspension and brake parts!