I feel that if you are thinking of rebuilding or replacing the master and don't plan on a completely original restoration from top to bottom then the smart thing to do is update to a dual circuit master cylinder.
While it may not be necessary it is a huge safety improvement. If you are questioning if it's a good idea to update take this test:
While driving around on a normal day think to yourself every 3 or 4 minutes, what would I do right now if I had no brakes the next time I stepped on the pedal? If you don't have a good answer every time then you need a dual circuit master cylinder.
Once you have made the dual circuit decision then think about a booster, if you have disc brakes a booster is a must.
Grigg
