1989 Mercury 8 horse to 9.9 horse conversion

[Chuckak]

I was told the the 8 horse and the 9.9 horse engine were the same except for the carb and the prop.
I would think I would need to change the magneto advance curve too.
What do I really need to make this 8 horse engine into the 9.9.
Is this doable?

Thanks,

Chuck