I can't answer your question, but I can ask you another - why do you want to do it? I know for a fact that a well-known and much maligned yacht charter company operating out of Port Solent converted many of their fresh-water cooled Volvos to raw water cooling, due to the unreliability of the fresh water equipment. Admittedly this was partly due to the custom of many of their punters attempting maintenance on the units, for reasons unknown. However, the advice of my son, who did much of the work, was never to own a fresh-water cooled Volvo.
This is second-hand info, of course, but as I remember from discussions with my son the main problem was the made-up pipework that slots together using small rubber seals. These seemed very unreliable and became dislodged easily. The standard fresh water pump will only take these fittings, as will the heat exchanger, so it is not possible to throw the fittings away and replace them with hoses. The fittings are definitely of the one-time-only variety, and no amount of sealant will make them seal for a second time.
I can't say whether I am discussing the same engine model, I know very little about Volvos, but this happened within the past 8 years or so.