rcmk motors

hi one and all    i know rcmks seem to be good motors as i have two zenoah motors  ones a very old 23cc and a 26cc both have a 257 carb.
Any way the question is has any have a  rcmk 30r   or rcmk 30rz  as im looking at getting one for a hydro  .
Im thinking of putting one of these motors in this boat.

the other thing is if they are great motors i will look at putting a side exhaust for my acr42 cat .
thanks for any comments