Careful!
Do NOT use the boom as a lifting member. The lift should/must be provided by the halyard from the top of the mast. The halyard is pulled towards the aft end of the boom with a piece of rope tied to the end of the boom. (A boom vang would work nicely here.) I just recently used this method to lower my new 3GM30F into my 33 and it worked just ducky. My biggest problem was getting the engine back aft onto the engine bed, and that just took a good solid shove as my helper eased the halyard off the coachroof mounted winch. The 3GM easily weighs twice what your Renault does and it wasnt a big strain so I can't see it being that big a problem for you.
