It's been a long while since I last visited. But ROCK ON!!!!! This is what I've really missed. I too have a 91 300E with a M103. Having just done the entire exterior body to a E500, it's now time to lay it down. I was leaning more towards the C36 setup which is the most straightforward, and also maybe a later model M113 engine/ 722.6 trans setup which is a little more involved. But I'm now leaning towards the turbo setup. Thanks Guys!
I will have to read over this entire post thoroughly. I was wondering if a turbo from an 88 Toyota Supra would be of good use? I have one left over with the manifold and piping from an engine swap I did a while back to a friends car. That too was a 3.0 liter. Locating turbo accessories will be of no problem, I have close touch with many salvage yards around my area.
I'm sure that all the guys from my shop will be very excited/helpful when they hear of this plan. Keep it comin'!!

Bill
91 300E
Done Up