I would recommend getting something a bit newer, those skis will have a top speed of about 35mph and in rought water will be all over the place. I would look at a Yamaha GP1200, GP800, Kawasaki 15f, Ultra 150 or SeaDoo GTX. There is an aftermarket for all of those ski and they will all do 55+ stock.
If you can't find the model you are looking at here, then there's not really any aftermarket support.
http://www.rd-performance.com/performanceKits/index.asp