The problem of the pressure plates, front and rear, rusting to the drive pulley is not at all uncommon on an Original. They can stick from setting out overnight in the dew. Clean them up good and you may find that the lining is still on the pulley. I have owned somewhere between 15-20 Originals, including a prototype, and have only seen one that the lining was messed up on, and that was because someone tried to glue a clutch disc from a later model on the pulley because the clutch was out of adjustment and was slipping.
While you have it all apart to replace the lining, reface both pressure plates, either by sanding or in a lathe, and check the driveshaft for wear in the area that the drive pulley spins on. They will wear under the pulley bushing and contribute to the clutch sticking problem. You can try to weld it up and turn it down, or replace the driveshaft (which is still available). Put a bit of white grease in this area when it goes back together, and with the pressure plates refaced, it should about stop the sticking clutch. Notice I said "about stop" it from sticking. I always park an original with the tractor out of gear and the clutch pedal locked down. And if it sets ahile between use, make sure the clutch/pressure plates are free before you start the tractor. If you start it and the plates are stuck, I can almost guarantee you will run it into something, when it starts, before you can get it stopped. BTDT