PBR, that certainly would be a nice power plant back there. You'd want to know what the dimensions are, particularly the width at the heads. A sbf is a pretty compact power unit and most V8s are larger, some much larger, particularly when equipped with single or double overhead cams, and not all will fit.
I believe there was a German CAV dealer who installed a merc engine in his CAV. If I'm remembering correctly, he unfortunately passed away in an accident in his CAV while travelling at a pretty rapid rate of speed. I don't know if that engine was an AMG or ??
Frankly, the SOHC V8 merc engine from an S500 is a pretty impressive piece of work. Lots of hp and torque and you can buy them used with low miles for about $2,000! I suspect you'll find that the 6.2 AMG engine will be in the range of $15,000-$20,000 if not more. Ouch.