I'm in need of replacing my single circuit master cylinder for my standard 66 model. Upgrading to dual circuit is tempting, I therefore need some advice on problem areas I may experience.

When searching for parts the 19mm cylinder from 69 on is available. Also a US dual circuit from 65 on seems on the market (17mm?). My car is a US model but has as you know a single cylinder. Was the dual an option?

What parts do I need in addition to new brake lines?

Any advice for this upgrade is very appreciated.

EF