I have a full line broucher for model year 1980 and there was no 500SEL, just the 450SEL. W107 is actually R107 and it is indeed the infamous "SL". The "116" is the chassis number for the "S" class cars produced from '73-'80. In the U.S. the W126 chassis followed the W116, starting model year 1981. I don't know the all the engine numbers for the gas engines. I am more familar with the diesels.
Are you looking to buy one?
1994 MB E320 Coupe (199,500 mi)
1992 MB 190E 2.6 (173,000 mi)
1983 Porsche 911SC (148,000 mi)
2004 Volvo V70 2.5T (198,000 mi)
President of CT/Westchester Section