Upgrade engine ???

Hi all together, to get right to the point, my cab currently equipped with nem 2.0i from 1996 (ABK), but I like son 5-ender already better (especially if he is forced to breathe 😉 ) and the question is now stop S2- or RS2 engine I get the front under ? Naturally I can save myself the chose and sell my cab and hold son thing but unfortunately there is only as Coupe or Avant and Cabrio driving is just now beautiful . I have also been feeling a bit through the forum The biggest problems are apparently chassis, brakes, cooling and quattro. I would think of the chassis, I already have an Eibach & Willms sports suspension. And suitable wheels I have a, RH type Zw1 225/45 R 17 ( stop 4-hole and ned as with s-rs 5 hole). Brakes and cooling must be ned so difficult bits of work stop. The problem is the Quattro drive, in the engine compartment has space without end, but below it looks barren. And probably i ch au amplify the body if the installation was possible. Look forward to answers, tips, etc. Thanks already in advance.