There's no guarantee that 571 endlinks will fit your case perfectly, due to variations in lug dimensions and hole placements on the reps versus the gens. Most of the time, they need some light modification to fit. Afterward, they fit great.
Not all folded-link bracelets have fixed endlinks. The detachable endlinks are denoted by a '2' instead of a '3' at the start of their reference number i.e. 257 vs. 357, 271 vs. 371. A 7835 bracelet with 257 or 357 endlinks should be a decent fit on most 6263 reps.
Ideally, you would want a 7835 with 271 or 371 endlinks, but prepare to pay upward of $1000 for one. Then prepare to destroy all its value by trimming those rare endlinks to fit!