You can get the gauge and sender from a 93 XP. It will work. But... on the older skis... they don't burn that much fuel. Besides... that's what the reserve position is for on the valve. When you run out... switch over, and head to shore.
Cool. With the issues with how slow it accepts fuel and the fact that I'm still new to the PWC game, I'd rather know for sure than let a nephew or niece float in the lake without a clue. Even though I'd be ok, it would just be for peace of mind