I would go 40 regardless of single or double, my single 45 on my a12 that's got 10 thou flat tops lightened flywheel h89 head with oversize ports and valves extractors inch an 3/4 exhaust and a mild wade cam still runs stupidly rich and chews juice like no tomorrow, in saying that it runs fairly smooth, is always a bit seedy until warm as they all are.
From memory I have 28 or 30 chokes I believ. Cannot remember for the life of me why mains and secondary's...