finrange would probably be between 26 and 33 cm. Best fins: freeride fins, so Select Supercross (if there's a lot of chop on your spot these fins are ideal), Select Rides or simular fins by any other finproducer (i only use selects so i cant tell you which fins from which brand).
For a sailrange between 6.2 and 7.0 i suggest you use a 30 cm fin, it'll be the minimal limit fin for 7.0 but it'll give you a sweet ride for sails between 5.7 and 6.4. If you can find a 31 cm freeride it'll probably cover your needs better.
But pay attention that in fin sizes it's the surface that counts, not dept, so in with one brand you'll need a 32 cm fin, with the other brand you might be able to get the ride you want with a 29 cm fin.
Haiko, AKA crazychemical