Overhauling a 1979 20ft MA

[ROBCAR]

another silly question I have is ....if i raise the transom another 5 inches, would i need to replace my o/b for one with a 25" shaft?

thanks in advance for any comments or suggestions.

by the way, i already removed the old wood from the transom and have the pictures of the process, but dont know how to post them.