Brzninski

Hi, I am a first time audi owner and have an allroad at 153000, but the damn body and everything else is immaculate and has been meticulously cared for. Paid $5000 for it. Has a ricking sound and hear its common but also know now after much reading that it could **** on me at anytime. Should this happen what motors that this car to do a swap ? I found one with under 50,000 miles on it for $1600 . That's cheaper than the timing chains/adjusters that would need to be replaced and since the engine would have to be pulled anyway wouldn't it make sense just to put a new/used engine in the damn thing ? Everything else is solid on it so I wouldn't have a problem investing a little money into it but I don't know if I should put a different model engine in it to avoid ever having to deal with the crazy timing chain issue again or the rattling start up. Any help would be appreciated again I'm a new guy to Audi's so give me a break if I sound a little uneducated. I already feel silly enough for not doing my homework on this and buying a car that could potentially blow up on me at anytime .thanks yall.