I understand your hesitation to cut open your baby, even when the time comes you have to do it to make her live.
I felt these engines a little mysterious until the time came that I had no choice. The M103 engine comes apart and goes back together absolutely beautifully. You need to use the right sealer on the upper timing cover to keep the seal from slipping out of place, I don't know any other real tricks to it. I did get a little confused over the cam sprocket bolts, turns out their torx.
You will enjoy the job very much,