97 sportster is a good boat. Since it has a fresh engine, it should still get into the low 40's, and it can pull a tube. The boat in my avitar is a 96 Sportster.
There really isnt' much to ask... other than what kind of oil he's using. Seadoo needs a Good API-TC oil to say alive. Regular "Outboard" TC-w3 oil is not good.
If you are thinking of buying it... take it out for a ride. It can run perfect on the trailer, but hardly run once it hits the water.
The boat should start, stop, and restart without issues. It should get going from a dead stop, with minimal cavitation. If you have to give it half throttle, and then ease up to get to full speed... it's going to need a little work.
As Boggs pointed out... the 951 Seadoo engine isn't know for it's life. Honestly... the 720 is probably the most reliable engine Rotax/SeaDoo put out.