OP, I think the thing that is most limiting for your buyers will be the age/design of the saddle: It will have a gullet and panels that don’t fit the modern WBs.
That said, I do think old Beval Devon’s are higher quality than are Pessoa saddles of the same age (they were made in Argentina by then) and they are certainly higher in quality that is Beval’s Stamford saddle and more recent ones.
If you want top dollar, however, you must have the saddle oiled and cleaned and photographed well. Take the stirrups off. Clean the whole thing. Then oil it. Then go over it with a damp sponge with high-quality glycerine soap in order to produce that soft shine that well cared-for leather gets. Do not photograph the leather fresh after oiling, with streaks of absorbed- and unabsorbed oil on it.
There are some Ebayers out there (like Maryland Saddlery/Scullion) who do a nice job with leather care and photography. Same goes for an on-line place like High End Used Saddles.
When I see dry leather like that, I’m uncertain about quality. I see from the maker, the craftsmanship and the grain of the leather that it should be of high quality. But when I see dried scuffs on the saddle, I wonder if this is some new leather that wasn’t tanned quite as well as the old stuff.
Just my .02.