80hp 4 stroke is a heavy lump compared to the rated 60hp 2 stroke i assume it is rated for. i couldn't find info on google re the max outboard weight of that boat (just says 60hp max and i assume 2 stroke).
that yam is 170kg and a 60hp 2 stroke is about 110kg depending on make-thats a fair weight diff to hang off the back.
i would say this is a no go.
twatsoo 75hp is only 115kg-maybe an option for more power assuming your insurance are happy.