You need to find or make a 2.3" spaced arm so that the geometry will be correct for your pull-pull cables. I have not checked my throw on the rudder yet but I am easily able to max-out the throw with the existing slots that are filed in the rudder. I'm not sure if I will need more than that (sometimes on Comp-arf's you need to file the slots a little longer.)

I used the wheel that comes with the BLS351 and made a phenolic arm from some scrap phenolic I had. You can make one from CF or G-10 or you may be able to find something long enough. The Dubro ones are not long enough. Several manufacturers make 2.5" aluminum arms that you could use - you'll just have to adjust the slots where the pull-pull wires come out slightly.

The BLS servos are REALLY smooth! And they sound really cool - the brusless motor has a lower tone to it.