Good to see your thread. Restoring a Maruti Suzuki. Is this golden color or Sand beige?
While the front of car is open, do inspect the cross member a.k.a Gadri of the engine as this part in mehran have a tendency of becoming weak due to rust eventually getting damaged.
The vapor barrier are thin transparent sheets applied with butyl tape between the door card and door metal. As i have searched thru forums in website like "The Automotive India" , i am sure that Maruti Suzuki india showrooms keeps a good inventory of parts and u can buy easily these sheets.
Your car color reminds me of a thread at "The Automotive India" posted by a member named "Varun". He had done extra ordinary mods to his alto 800 and he keeps his car pristine with regular maintenance updates. he called his car "The Golden Geese".