If you are interested, I have finally started the project of rebuilding my G320's engine, which will entail removing the cylinder head from the engine, and refurbishing it, and a complete engine bay refresh of all soft parts.
You can see the thread in the G-wagen section at this link:
www.500eboard.co
For reference, I did a similar job back in 2014 (hard to believe it's been 10 years) on a 1995 E320 wagon that I once owned. That job was fully documented at the link below.
www.500eboard.co
The E320 M104 rebuild thread has proven to be one of the most popular threads on this forum during its history, with more than 136,000 views of the thread.
You can see the thread in the G-wagen section at this link:

HOW-TO: M104 Top-End Rebuild (W463 G-Wagen G320) | G-Wagen Models
Tonight started the long-awaited beginning of my Top-End Rebuild for my G-wagen's M104 engine. With approximately 135,000 miles on the engine, the head gasket has finally given out, and is severely leaking coolant from the rear passenger corner of the cylinder head. This is about right on...
For reference, I did a similar job back in 2014 (hard to believe it's been 10 years) on a 1995 E320 wagon that I once owned. That job was fully documented at the link below.

HOW-TO: M104 / W124 Top-End Rebuild [Cylinder Head / Gasket] | "HOW-TO" Tutorial Articles
Well, this afternoon I finally got started on my long-awaited top-end rebuild project, for my wife's 1995 E320 wagon. The symptoms that precipitated this rebuild are the following: a couple of small, persistent oil leaks from the head gasket a moderate leak at the front timing cover The...
The E320 M104 rebuild thread has proven to be one of the most popular threads on this forum during its history, with more than 136,000 views of the thread.