By 1912 you could go for unlined black for some 1Fs but as suggested above, a photo would be necessary to ensure you have got it right. Having said that, there is nothing better than the full Johnson livery, if you are good at lining or have enough cash to pay someone to do it.
There was a transitional livery around this time of a sort of brown - if you are going for this, borrow a copy of Midland Style be George Dow. It has colour samples in the back.