The address used to be
http://www.drake-windsurfing.com/
But it doesn't work for several months already. You can see them here:
http://www.gunsails.co.uk/en/fins.htm
Drake Crossover 26/28 is comparable to a Select fsw 27/29, since the Select has rather small surface area for a given depth. If you want max alround range go for the smaller suggested. If you're after max power and upwind with a 6.0 then the larger.