Converting a 3 speed manual to 4

Is it straight forward, I don't know much about the early A's. Will the clutch linkage from the 3 speed work for the 4? I think I will also have to convert it from 3 on the tree to floor shift.

What are the ratios in the 3 speed manuals? Will the 4 speed make the little slant feel more peppy?

1964 Valiant /6