Purchase 1988 golf gti convertible

Hi guys newbie here im thinking of purchasing a 1988 golf cabrio gti 1781cc , Reg NO. E955 KWP in 2 weeks and looking for information where to looks for bad points good points what have you guys found  ect. All knowledge is much appreciated.
   Cheers Gogs

Welcome
https://vwgolfmk1.org.uk/index.php?page=cedi&type=misc&id=53

Or 
https://vwgolfmk1.org.uk/forum/index.php?page=_google_search_forum&q=Buying+a+cabriolet+

A tired top section is not cheap to replace.
So look at the headliner for orange bloom. Orange marks won't clean off. They often have stitch rot or are torn often dirty beyond cleaning.

Then there's the Interliner and padding.
Very few cars have these replaced,  often poorly attempted repairs which isn't any good.
Look for bits of grass like structure on the parcel shelf and seats etc. that's the Interliner and padding rotting away.
Turn to the rear window frame  check the lower edge from inside the car by lifting it up and putting your finger under there often you'll see rust bubbling there. 
None of that is cheap to do professionally.
You have to remember that all the old stuff underneath is over 30 years old and should have been replaced years ago.
If a seller says it's has a new top then ask for a receipt. 
A roof that's 5 years old isn't a new one.
Ideally take someone with you that has a good knowledge bases of all this. 
Welcome aboard