Steve, do you have a Metabo ra grinder in that pile o tools? The thing is terrifying to use with a thin kerf (.040") cut off wheel, it'll slice your hand off quicker then you could say oops. It would easily and quickly slice and dice the lead and concrete while coating every imaginably nook and cranny of your boat with dust. I use one with GREAT caution and fear.
I also use a variable speed Makita ra grinder with a chicken plucker and a concrete dust hood hooked up to a Fein vacuum for heavy fiberglass grinding. I love that tool for prepping glass, it's does a pretty good job of minimizing dust.
Dog, it's easy to add a little bit of refrigerant in the spring. When these things sit for a while (winter) the seals can dry out and loose some refrigerant. When you start it in the spring look at the plates and see where the frost line is at. You may want to add an ounce or two, no biggie.