According to BenzGuide, only is added just to the point it starts to leak from the filler hole. According to the following photos, the Mercedes SC is mounted on it's side in a similar way that I will be mounting it. The filler hole also appears to be at the bottom.
A quote from the site "Supercharger Oil must extend up to not more than lower edge of threaded hole". This means that not very much oil is needed at all.
Use Mercedes Oil Part#: (A 000 989 62 01). or Mobil Jet Oil II. Looks like the GM SC oil is good enough also.
Use silicone gasket-maker to re-seal the case halves.
double row bearing (measuring DIM ID:30mm x OD:47mm x W:22mm)