Complete due diligence is the best way forward.
What is needed is as much evidence as possible, and preferably validated by the authorities.
All this is easier said than done.
VAT paid and / or reclaimed is irrelevant. The correct procedure at the time the goods were imported is.
The term that needs to be considered is: "In Free Circulation".
Depending on the goods (aircraft) the place of import, importer status, in recent cases point of entry, and the date of import defines the VAT (& duty) paid (if any).
Whatever may or may not be reclaimed afterwards is irrelevant.
The EU has a Single Administrative Document (SAD) that is known as the C88 in the UK. This form has the same layout / format in all EU languages, therefore if you take any foreign language form and compare in to your common language form you will be able to do a rough translation. Especially as the key parts are numerical.
The C88 SAD kicked in in 1988 so a 1992 aircraft should have one.
This document can be, but not always easily, validated as the office of import keeps an 'original' copy, in theory. These days it is generally electronic however scans etc. are kept on file.
Obviously all other documents pertaining to ownership, transfer, sale, purchase etc. etc. should be kept and / or requested as this builds the 'case' should there be any customs queries.
For aircraft, any customs import document should carry an original wet stamp. i.e. the end result of an ink pad and rubber stamp. Regardless of the computer / electronic output of the paperwork.
Be sure that 'Box 1' (top, just right of centre) as 'Declaration / Regime' shows "IM" for import.
Be sure that 'Box 31' (description of goods) includes the aircraft serial number and full description. A tail number alone is not sufficient.
A UK C88 / SAD should look something like this:
http://tinyurl.com/bt6g3q4
Other EU SAD's should be pretty similar.
Apologies, but it has been suitably edited / redacted etc. however the blanked out sections are item specific but I hope it gives a rough idea of what you should expect to see. This one is for an 'N' reg aircraft.