Upgrading aerobars on P1 from cervelo branded bars to Zipp Alumina. The old brake levers have a larger diameter than what will fit in the Zipp. And yes I backed out the expansion screw. Are brake levers diameter standard? I believe the P1 original brakes are FSA. Is this a Zipp or FSA custom thing?

Can someone point me in the right direction and if I have to replace, what do I do I need to be looking for?

Thanks in advance