Once you take a salt water jet and run fresh water through it awhile, should clean up the scaleing I would think. Pitting would be another issue.
Sounds like you found a boat, if you're comfortable with the price. Fresh water boats have their own problems, such as sand in the block, etc. The main thing is the boat. Engines and jet drives can be easlily replaced and rebuilt. In this economy, you can buy replacements at bargain basement prices, so I would worry about the hull and whether you like it or not. And whether it's a deep v or very shallow v for your intended use. (Or tunnel, gullwing, pickle fork or whatever).
Have (or HAD) 1 of about everything, the deep V was a great cruiser! My shallow V (and VERY shallow) is a kidney buster, but I'm getting better driving it to avoid a lot of that bouncing! The Hallet I got from B-Rad, lord I dunno, much flatter than the Moo and I'm thinking a Blown engine in the Mofo! (we got sumthin planned Brad, you're not allowed to know.....)
Terry's gonna show me what bouncing is in a couple weeks in his flattie I'm sure!
Ray
Someone, Glenn (GT) Most likely, will chime in with much more knowledgeable information I'm sure.