Bummer about the paint! Hopefully the shop will make it right. About the valve stem seals... it's a long shot, but perhaps one or more dislodged and is floating on the stem? I had this happen on my OM603 after paying a machine shop to swap the old valves into a new head; it was pushing a moderate amount of oil out the exhaust. Turns out one of the aftermarket seals didn't stay in place on an exhaust valve. I bought the tools and replaced all the seals, this time with OE, and it was fine ever since (over 100kmi). Wasn't fun, and I didn't know what happened until I had everything apart. Since it was a brand new head at least I knew the guides were ok. Pics attached.
Excellent. 9110 works perfectly to press in the new-style Sportline rear bushings. Just a heads-up on the 9113, the threaded shaft is ~12.5mm diameter, and doesn't fit in W124/R129 diff mounts. However... OE replacement mount
129-351-50-42 has a 1mm metal sleeve inserted in the middle for the M12 bolts. I don't know if it's easily removed/installed, but if you can pop the sleeve out that would allow the Miller shaft to work. Otherwise you'll need to rig up a threaded shaft that is <12mm diameter. The Miller dies/sleeves should all work fine.