Gus, if you have a crane that can lift...
the mast off the step plate, then you should be in good shape to do it yourself. The crane boom needs to be at least high enough to reach the upper two thirds of your mast so that it does not flip on you. You will want to do this while the boat is on the hard, IMHO. Otherwise, hire an experienced crane and operator to do it for you. Be sure to mark the chain plate turnbuckles with a piece of tape so that you reset them at the proper tension, assuming they are at the right tension now. If you are not sure then hire a rigger.Terry