I'll be surprised if the M110 engine will have enough hood clearance in the W113 body. The M110 engine is taller having a large wide and tall cam box for the double overhead cams. You would be adding a lot of complexity for not much more power. I would be thinking of using the later straight six, single overhead cam engine out of something like a 300E. It is Smaller, lighter a lot simpler and has more power than the M110 or M130.