I put a 90 HP ETEC on my SR4.7. The engine weighs 145 kg.
before i bought the engine i tested my boat adding 40 kg lead on the transom. This way i could simulate the weight impact of upgrading from 65 hp to 90.
My boat is rated for 70 Hp and about 130 kg. However it works perfectly well even it's "slightly" overpowered and overweighted.
I didn't feel good about it before the sea trial. i actually thought about it for several years and started a few threads here about the subject.
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.