|Note that the article says, "The Yanmar 2GM and 2YM engines are virtually a drop-in replacement. You don't touch the glass (see Ralph's comment above). The steel angles on top of the fibreglass or wood beds need to be changed, but anyone who can use a measuring tape and hold a hacksaw and a drill can do that."
I had to take my original steel beds out and replace them to get the engine to the right height, but the difference is only in the bed height, not the width, so you don't have to do any glass work. That would have been a problem; drilling a few holes in steel angles then bolting them back in was not.
While you're in there with the engine out, replace every hose you can see. You'll never have better access (and you'll need to put in a larger exhaust hose). Also, I suggest you stick sound insulation to, at minimum, the underside of the cockpit and all the accessible areas around the front of the engine.
C&C 27 Mk IV