evintrude 15hp identification

hi all and thankyou for letting me join your forum, my name is James i live in ENGLAND UK, was wanting to know if anyone can identify my evintrude engine i just purchased with a westline dinghy 2.3 meters the serial plate reads......5522B 51463..... I have been online to try and identify the engine but all the info i have looked at on evintrude page has not turned anything up, the engine itself has 3 knobs at the bottom left to right first knob you turn says slow speed, 2nd knob says fast speed and 3rd knob is pull for full choke. The engine runs very well and pumps water great but i am in two minds if its a 15hp seems a bit fast. Any help would be appreciated, thankyou.

That is shown as a 1961 model 5.5 hp.-----But post a picture if the motor if original decals and paint.----Easy to identify.