As far as I know, nobody's been able to get the SL55 (etc.) engine working with the SLK55 electronics.
Just my .02,
There are several Crossfires (and r170's) with the M113k engines swapped in. One of them is down here in South Florida running 10 second 1/4 miles without any juice. Check the Crossfire forum for details. It does take someone with a deep wallet and a tech with extensive ECU programing knowledge to get something like this done.
If my memory serves me correctly there's also a shop in the Midwest that put a m156 into a r171 and also did a few of the V8 Crossfire conversions. I could have sworn I read about it here on SLKW but I cant find the threads. Last I remember reading, he started having frame issues for one reason or another.
Maybe, a better question than the one posed by the OP might be; how much power can our little SLK chassis handle?
For example, I only have a set of Thermoteched headers, an Eurocharged modified ECU and TCU, and a set of Green filters. Everything else on the drivetrain is bone stock other than reasonably fresh fluids and plugs. I can still boil the 275x30r19 tires I'm running from 20mph. Without tubbing out the rear and shortening the secondary shafts, there's absolutely positively no way you could fit a tire wider than 275 under the fenders.
kleeman offers a fine tuned system with only 0.5 bar.
The Kleemann blower is such low boost because the N/A motor in the SLK55 runs a high 11.0-1 compression. They cant run the boost up much without deto. The OE 113k motor runs 8.0-9.0 CR (depending on who you ask) and boost closer to 1.0 bar. So presuming each of the blower compressors are of similar capacity and efficiency, the 113k would outperform a similarly prepped Kleemann blown SLK55 motor.
Traction aside, starting with a stock m113 and adding a low boost Kleemann blower, a larger throttle body, some cams, a decent porting job, and a free flowing exhaust would also likely make enough HP to get you to the limits of the stock SLK frame. And it would cost about the same to do a 113k motor swap, warm it up a bit with bolt ons, get all the electronics to play nice, and then sell the N/A motor. The latter would also get you to the limit of the stock frame given that a SLK63 seems to be able to bend it.
As for me, I just cant seem to convince the wife why it's so important to spend $10k - $15k to be able to put a "Kompressor" badge on the fender of our $20k SLK55. But that doesn't mean I'm giving up on try'in tho...