Thanks for the links .

The model 860 from Vishay will fit the bill exactly.

"Make sure you use a heli-cal flexible coupling between the pot and the sensed member "

A good warning. Not only that, in my case I will be biasing the mechanical zero at 50% of the electrical travel as I need 4.5 rotations on either side. In such cases we use a precision slipping clutch along with a bellows coupling to connect the pot shaft. In case of accidental overtravel beyond 4.5 turns I need to protect the pot!! ( This was one consideration in favour of Encoder - anyway thats gone now.)

Raghu