M103 Head Done, Still using oil

[savas]

Car:1989 300E M103

I recently had the head fully redone on my M103 at 249K miles by my indy mechanic, a mercedes indy shop which I've been using for years. I've been tracking oil usage for the last 5 months and it's still using a quart about every 6-700 miles. I pulled the plugs and they all show signs of oil usage. I took it back to the shop, and they took a look. Their conclusion was that oil must be coming up through the rings because all spark plugs showed oil usage. Although I don't have the numbers in front of me right now, the compression was fine and even. They also looked at the head through the spark plug holes and said it looked clean.

I'm trying to consider my options of what to do. I was considering using rislone ring seal to see if that may slow down the oil use. Any other suggestions?