Could be a number of things. First off, I'm going to assume you still have the original rubber centered clutch disk.
Does the noise change when clutch is disengaged?
Does it change if the car is idling in neutral and you start to push the gear lever into first (without stepping on the clutch pedal and without actually engaging first)?
Does your shift rod have the rubber band o-ring?...
Later G50s also got an updated clutch slave cylinder and a brace, 950 301 401 00, between the trans case and heat exchanger, #24 here...
Also, this...
