I would say 40 - 45mm webers on an A-15 as the recommended choke size for a hot A-15 is 36mm. I would think that the power output difference between carbs on the dyno would be marginal.
I run 40's myself and have had great results. I guess a pair of 42mm DCOE's could be considered aswell. Jet selection is the key to performance aswell as aux vents and chokes. This is the black art stuff. Some could argue that a well sorted Weber setup is as or better than EFI. Some top level sports sedans still run carbs.

Benny

yeah benny i have twin 40mm webers on it at the moment but im chasing more power so im just deciding to go all out or find a happy medium

The size of the butterfly is not going to give you power per-say [spelling]. If you are chasing power in the A-Series I would be investing in the cylinder head. port shape and size, valves and valve weights are where the gains are to be made. Cam selection is to be considered aswell.

What are the jets, aux vents and chokes you are currently running??

jeez benny youve got me there? i think 33-36mm chokes john cain did my tune on them around a month ago but dad sorted that out.ill find out the jets and let you know too
benny are you comming to the supersprint at bathurst on december 2?

I can get quad throttles off a 1100cc bike on a oval port manifold for $250 if anyone's interested. No wiring, injectors (standard falcom/commodore/nissan) or fuel lines. Comes with sock filters.