Is 120hp too small for 21ft center console

[gotomgo]

Rod knock!!! Think I have it pin pointed to cylinder 1.i. Having horrible luck with outboards this year and the people selling them to me. I have a 98 merc125 offshore motor I got as a package deal. It is supposed to be a good motor but previous owner broke 2 plugs off in motor. I was able to extract them this morning.but now I gotta remove my motor from boat and swap all the parts I robbed off this motor...