Yamaha conversion pump/prop

[Drfter]

I am trying to change my 2006 Yamaha 115/80 from a pump to a prop. I currently have a 20" shaft and need to go to a 25" shaft.What parts do I need to get to make this happen? I have been told to buy a 25" lower unit and then i need to get a 5" extension to make this work. Any help or even part numbers would be greatly appreciated.
thanks

[boats.net]

You would also need longer shift shaft and longer water tube(the ones from a 25 inch shaft model) which means you would have remove powerhead to change them.