I agree the 8hp is too big, but I wonder about a buddy who would sell a 20 year old motor for the outrageous price of $450? If you go to this link it rates a 1987 8 hp Evinrude for $100. You might want to check out this site if you are considering buying a used motor.
http://www.nadaguides.com
I got the link from another forum member a couple of years ago and am glad to pass it along.