Hi,
I hope this helps. Your boat came with a 1" inch diameter prop shaft. Off the top of my head I don't know the exact length needed. It's roughly 42 inches. Do you have a usable strut? Prop? Prop shaft log?
Take a look at this catalog from Marine Hardware you'll see what's available. You might call them and they could advise you. http://www.marinehardware.com/downloads/running_gear.pdf
Also you can contact Ron Tanis at Skiboatpartsonline.com and he might know what prop shaft you need too. http://skiboatpartsonline.com/Inboard-Ski-Boat-Parts/