Ben,
Have a look at the Centreboards thread again. The best thing you can probably do without rebuilding the hulls is get the maximum rake angle of 10 degrees and modify the centreboards to suit. My Mozzie is pretty old and was built with 5 degrees rake and now it's 10 degrees due to some minor modifications (see thread).
Regards,
Peter
p.s. My centreboards are now 1050 long X 250 wide and they work just fine. <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />