There is a maximum amount of rake allowed in the building restrictions, as follows.
5.11 The leading and trailing edges of the centreboard slots shall be parallel and within 10 degrees of the perpendicular from a straight line along the tops of the main and rear beams.
There is also a maximum distance aft, measured from the bow.
5.2.5 Aft edge of centreplate case 3353 mm maximum;
To my knowledge most Mossies in the last 25 years have tried to use both of these to try to get the centreboards back as far as possible, which has allowed the mast to be raked further back which improves upwind performance in strong winds and reduces nose diving downwind in the same conditions, whilst not making the weather helm to harsh. Theory the further back your centre of lateral resistance (mostly attributable to centreboards), the further back your centre of effort in the sails can be placed whilst still being balanced.
The 4mm ply Carter boat I had in the late 90's early 00's 1111, had the centreboard cases blocked with foam top and bottom to give the maximum 10 degrees back, at the same time being as far back in the original cases (that look like yours) that had been placed in the boat (not the maximum distance aft).
I don't think there is a down side to having the centreboards back as far as possible, but there is a downside in my opinion to angling the centreboards, this effectivly increases the width of the centreboard and reduces the efficency of the foil and incresing drag, also reducing the lift as the leading edge is angled back.
So after putting new vertical centreboards into 1760, I am convinced that vertical centreboards can be used effectivly in Mosquito's in all conditions as long as the cases are as far back as allowed in the rules.
If the back edge of your centreboard cases are not as far back as allowed in the rules, I would try to angle your centreboards back to the maximum 10 degrees.
