VW 16v KR engine in Audi 80 Type 81

Evening… I just remembered that I wanted to ask something. I have an Audi 80 Type 81 GTE as 2nd car. At the moment I drive it, but soon my 90’s Quattro. In the 80’s there is now a 1.8L engine in it. The previous owner has mounted a different head (from the Quattro PV), why ever. I have now Weber on it (very strong!!!) and I like that really well. The engine now makes so slowly sluggish. Now my question: Does the 1.8L 16v KR motor from the VW pallet fit into my My girlfriend drives a Jetta 16v and he’s doing so well, and in an Audi a 16v with Weber, that’s what I’d like to do. Or which Audi engine gets the power and the noise? And what would the nice gentlemen of the TÜV say about it? I now have a U-Kat engine in it, so the 115 hp series. It wouldn’t be a retrofit. I hope one can help me here too… Thanks for your answers…