We are planning to replace our old oil fired steam boiler with a new energy efficient (Hallowell Acadia) heat pump w/central air. Obviously, we need to install an entire new duct system. Our house(around 1880)has a stone foundation with large stone slabs on top of the stone. There are a couple places where we need to get access to run the new ducts into a crawl space. The slabs are about 18" high and 6 or 8" thick. Is there a good way to do this, such as a rented diamond blade power saw? The ones I have seen are gas powered and are probably too large for the tight quarters we will be working in. Also, what type of tradesman would do this kind of work? Thanks for any info!