I have a Yanmar 3GM30
in my 323, it seems to fit just fine, although anything in the 323 will be pretty snug. I can upload some pictures tomorrow if you would like to see the fit.
One thing you may have to get used to is the transmission
being the opposite. On mine lever forward is reverse and backward is forward. This was not a big deal for me since it is my first boat and was able to get used to it this way. If you have any other specific questions about transmission
used, or other details, please ask, and ill try to provide what info/pictures I can.