Twin master cylinder setup

Hi,

I'm  planning to do a servo delete and want to replace it with pedal box on an original column, but I'm not really sure how to work out what master cylinder sizes I should go for? I've tried searching the forum, but couldn't really find anything. Any adivce on how to work the sizes out, please? Anybody have converted theirs and what sizes have you gone for?

Thank you for your help,
Michael

Edit: Sorry, just realised I posted in the wrong section, please move to the correct one