[onewhippedpuppy]

For your price range, might as well remove the 993 from your list. Nice ones, even with high mileage, are nearly always $30k+.

For a water pumper, take a good hard look at a G50 Carrera and 964. The G50 gearbox is a huge upgrade over the 915, and the 964 improves the entire package in a big way. Have you looked at a 964 in person? In my opinion they don't photograph well and look good in person.

Also take a good look at the 996, they are fantastic cars and easy to live with daily. Simply the most Porsche bang for the buck right now. You can get a 2002+ for your budget which brings a bigger 3.6l motor, better interior, and a host of other improvements.