Excellent write up! Those actually appear to be the 6 piston calipers, of which many variations exist. The 8-pot versions use multiple pads, and are often not as high performing as the 6 piston versions.

I also have an M113K swap car, and have been working on the brakes. I just went to the SLK/CLK55 4-pot rears, but had not quite worked out the right combination of parts up front. Currently I have C43 AMG 345mm front brakes. I have a pair of 2013 CLS63 6-pot front calipers that I plan to use for the next upgrade. The rotors seem to be the real trick. I have CLS rotors (one piece), W211 Brembos, and R171 SLK55 Brembo hats. The CLS and E class rotors have too much offset, and will make the rotor hit the spindle. My plan is the move the SLK55 hats to the E class rotor discs. This should give me the thicker 36mm rotors on the correct SLK platform offset. This is a bit theoretical, as I haven't found the time lately to try. If you could shed more any more light on your setup, if would be appreciated.


Adding on. I did go with a closed 10mm hub centric spacer up front for the C43 brakes. Preliminary mock ups on the car with the CLS63 caliper just bolted in place (temporarily for fitment) showed clearance on the stock 18" wheel.

Also notice that I went to longer wheel studs and nuts up front. This was a great upgrade, in of itself. It did correct the thread engagement from the spacer, plus these are actually stronger than the factory lug bolts.