Audi 80 winter car

Hey guys and girls, I bought an Audi 80 as a winter car but it has already run 230 tkm… I really like the audio quite well from the look and I decided to build it a little bit on, now I want to ask how ruboust such an Audi engine is or is it not worth it anymore to plug in money at 230 tkm? Ahja and the cat is broken someone can tell me what a new one costs? Mfg Matze