I set up a Martin Tracer 26.5" @ 60# for a buddy, and we went with a LONG 28" arrow, because it helped get the spine where it needed to be w/ a 100gr tip. You can look at GT 3555 series, or whatever else you find in a 500 series. The shorter you go, the weaker spine you need, if you go with something 25" long or so, you're gonna need a .550 spine to be "optimal," keep the arrow longer 27-28", and you can get away with a .500 spine, which is more common.