For Berowne and anyone else who's interested here are some distances mast track to fin box for for the SLW 90 .
Using the base at @ 30 m/m back from centre at the moment with the switch fuse (slingshot wsf1) orientated so the front wing centre line (port to stb) is directly under the front screws of the rear straps.
As mentioned I am using a 9.0m NCX so I can apply considerably more downforce than say a 6.0/7.0
Centre of mast track.

To centre of front straps 520 m/m

Centre of rear straps 1070 m/m

To centre of fin box 1150 m/m