Honestly, conformation really doesn't play a very large role in whether a horse will be a good endurance prospect. It's all in her mind and metabolics, though it helps that she's not built like a twig or a tank. Beyond that, we really can't tell you much about whether or not she'll be a good endurance prospect - you'll just have to start conditioning her and take her to a few LD's or 50's and see how she does. Some horses are great for the first 20 miles or so, and then absolutely shut down and decide they're done. Others have the will and metabolism, but are total spazzes on the trail and so make it miserable the whole way. You'll really never know until you start riding her like an endurance horse and see how you two work together and if you like her!
I used to be worried about conformation, by the way. Then I saw pictures of all the awful shaped Tevis horses that are successful and my veteran endurance friends said conformation doesn't really count for much (and definitely doesn't discount your horse much!) in the world of endurance.