I think there is another question you might have to ask.

Is the gearbox crossmember the same for the 4 speed A12 and the A14 5spd box?

The answer might be no...

This might mean some fabrication, customisation to get the gearbox happily bolted to the chassis.

Quote:

After I posted that, I went out and took a look at the box. It has the slave cylinder still on it, and then I realized that a longer line was all that was needed. (DOH!)

The Sunny crossmember is also still attached to the box. It would be nice if the frame rails are the same width, but I usually don't get that lucky...

1200s don't have a frame, so no frame rails. Instead, the rear crossmember (at back of transmission) bolts to two bosses that are inside the transmission tunnel. To fit a 60 series transmission, you can make up a bracket out of a flat piece of metal. See tips on installing a 5-speed. I don't know if the 63a will fit the same, but probably will as it uses the same mount.