I have a 1979 Mercruiser 120. I'm looking to change this out and already know that a 140 is an easy swap. My question is what others (if any) are fairly easy to upgrade to. I seem to find lots of 470, 165, 3.0 engines. I currently have the original merc 120 outdrive as well but I'm also looking to upgrade that.<br />My goal is an economical, reliable powerplant that will be relatively easy to install and that I can find a good deal on.