I have most CA-boards. Forget sail size. It is all about the boards ofo.
SP50 - C3 Venom 26 or 28, also Tectonics F1 26.
SL 55 - C3 venom 26 or 28, tectonics 26, - or weedfins like Hurricane 24
SL62 - I use slalom fins on the 62, Black Project or C3 Sting 2, 34, 36 cm
SL72 Do not have that board, but I use Black Project slalom fins 38-42 cm on SL75 and SL78.
//Anders BQ
www.andersbq.com/2012/02/premium-speed-fin-test.html