By normal conventions SA/D is cited for a boat with its 100% foretriangle so the SA/D for your boat would be something near the 21 with the the
jib rather than genoa. A SA/D somewhere above 21 should yield a reasonably good light air performance.
As I mentioned I have not sailed a Bluenose and was basing my comments on similar boats and their lighter air performance. Normally these narrow, short waterline, low freeboard boats of that era were not able to carry much sail area without being overpowered in higher winds. An SA/D of 21 sounds like a lot of sail for a boat that narrow.
One thing about some of these older designs they sometimes have surprisingly little wetted surface compared to a boat like a J-24 which is beamy, comparatively flat bottom. If that is the case with the Bluenose, given its comparatively large sailplan for the type, it might actually have good light air performance, perhaps at the price of being a real handful in heavier going.
In any event, the proof will be in the pudding.
Jeff