Control box for 25hp 1999 johnson

I purchased a 25hp Johnson with control cables and control box,it's a one lever type.
I am running a 1963 18hp Evinrude two lever setup on the boat at the moment.
I have the johnson on a stand with the control box and cables attached.
I will need to change the cables for longer ones when I fit it on my boat.
The lever does not operate the accelerator or the gearchange,it has a function where you can pull out the lever which allows the lever to move.The cables are connected,but they don't move the cables at the outboard.
Am I missing something in the operating procedure?
Also,would it be possible to keep the two lever system that's already fitted on the boat,and fit new cables to it.?
Bearing in mind the difference in the 1963 and 1999 motors.
The cable ends look the same at the engine end.