Hi Stefan, the moke looks very repairable, they all rust in the battery box but in yours
it may have also rusted in the 'Bermuda Triangle' which is a trianglar shaped space
cunningly designed by BMC to rust out, all fixable, just depends on your paitence, skill's and wallet
When your there next check out the engine number, if it starts with 9 then it's a 998cc, 10 = 1100 and 12 is for a 1275cc motor
The Vin looks like YJBAB1R 3371 so my guess is a late 67 but as you and others have said the early ones have no date stamped
on the plate and they started at 501.
If it's been there for 20 years it must have a low milage, do you know why it was parked or did he decide to buy a Holden One tonner
What is the small car in front of the moke? looks very interesting, Austin 7 special or Lotus 7 replica