hi john, you are correct as in the last 5 numbers (from factory) of the car VIN were from the engione number and as such these should both match up if its the original engine.

ive never heard of a factory restamped chassis plate though. what does it say on your log book ? you can request for a few quid a full history from dvla of all changes that have been applied to the car since 1st registered - which will show all previous owners, cherished transfers/private plates and any changes to the car ie, colour, wieght, engine number etc.

you need to check the engine number itself - not just the ally plate on the slam panel...

example of original escos VIN:


and location of engine no on block: