in general, i'm grabbing my 6'2"x19 3/4"x2 7/16" CI Dagger squash tail w/ SOAR LE8 tri fin set up from punchy stomach high to about head high. lower entry rocker, plenty of tail rocker=paddles easily, but still fits tightly in the pocket.
if it's bigger or more powerful, i'll use a 6'4"x19 1/4"x2 1/2" CI Ft. Knox round pin or Campbell Bros. 5 fin bonzer, also a round pin. more entry rocker, pulled in tail, still fast & drivey down the line but more control w/ the pulled in tail. the 2 boards are nearly identical in outline & rocker, but the differing fin set ups change the whole experience.