From Carve 131 to Futura 133 or ..122 ?

[DJluc]

Hi,

I will be changing my C131 ( best board I ever owned !!!! ) for a Futura.
I'm 75 kg and sail in 7 - 21 knts flat water with 6.5 / 7.5 / 8.5 sail.
going for width of C131 ( 71 = fut 122 ) or volume 131 ( =fut 133 ).
What to buy ?
and what fin size for 3 sails ?

Thanks for help.

Luc