I've only ever seen one mk1 with an Audi TT dash into it and I think it was covered in PVW last year (2005) silver mk1 - had complete Audi TT engine conversion, power steering etc installed too - looks the business, but was a nightmare to install quoted by the owner. Worth the pain I think...
I prefer old skool mk1 dash myself or a BMW 3 series Dash or Corrado Dash for a mk1.