yes 560 sel indeed would be a good choice. It comes with 240hp stock. there are several things that can be done with it (remember that engine wise bouth coupe and sedan have same dimensions and specs). At mbcoupes.com one guy has installed a european 560SEL engine in his car putting out 300hp. Another guy has put a 500SL engine in HIS car, if you go to mbnz.org there is a guy (superchargedsec) that has supercharged his 560sec. If you just want the looks e.g euro headlamps, clear corners, lowering, wheels etc then go with the 420SEL. Just my opinion.
Hope this helps