lightening car

i need some ideas on making the car lighter (72 dart)

i have no interior except 2 race seats, harnesses, and rollbar
i need to try keep the dash for originality
i have glass front bumper with alloy irons and glass bonnet

i dont want glass fibre doors as they are a pain, i also want to keep the glass

any ideas please, especially on how to lighten say the doors, or trunk etc etc