Your 5.7L Volvo engine is a 350 Chevrolet engine marinized by Volvo. If the 350 Chevrolet engine you are planning to use is not a marine engine it will not work. I would recommend checking the following links for some of the differences between an automotive and marine engine - http://www.boatfix.com/how/marineeng.html - http://www.marineenginedigest.com/specialreports/marinevauto.htm - This should give you an idea of why you can't use an automotive engine or parts on your boat engine. I hope you find this information helpful and let me know if you need any other assistance.
Marine Mechanic
11 years experience working on outboards, inboards, sterndrives & pwcs