An age related plate is a long shot, you may be able to visit your local DVLA and explain what has happened they MAY be sympathetic. For the Engine age you can use the chart in the link below to prove block age:
http://www.burtonpower.com/technical...ate_chart.aspx
Show this to your IVA tester and he can check block age from the first 2 letters of the number. I tried with Ford to get a confirmation letter and got no reply, the chart was okay for my SVA tester.
All the Best....AndyH