1993 williams with 150.000 miles.its been sitting outside for 3 years and hasnt been started in that time but was going well when parked up.i havent seen the car but was talking to the owner on the phone and he is looking £500.the car was stolen when a few months old and had its interior stripped out so its got no dash plaque.it was replaced with a 3 interior.any ideas on the cars value?