You should keep it stock.
The W126 was neveR meant to be a two-tone car. This kind of customizing does not look good and diminishes its value except to the customizer himself, in most cases.
The Manganese Brown color is actually rather rare, (this is a manganese brown 1983 500SEC euro of member "CamelotShadow" in Los Angeles
and if I were you I would go for a really good repaint.
Rather than "two tone" if you must do this, the W126 Gen I vehicles (1981-1985) could sometimes be found with complementary colors on the lower cladding on the sides, fron and rear bumpers - and mirror backs.
As seen on my car:
But the best thing to do would be to paint those pieces in the matching original body color.
The previous owner of my car (admittedly a last year Gen II coupe) in body color..
A nicely refreshed manganese paint job would look great in that scheme.
And a set of chromed or brushed Lorinsers
These are the ones I used to run as seen on my car about 15 years ago:
:
and now have been cleaned up and are on SiNIK84's 1984 300SD
Note the attractive front and rear euro bumpers on it that he's installed.
And the must-have euro headlights of course.
This Gen. I shortie diesel example - seen on a Calif. Delta river cruise, last year, looks nice in Manila beige with its factory painted gray lowers and bumpers
or (W140 8-hole replica wheels from Tire Rack ( a site sponsor) would I think Look very very good at a reasonable price and be easy to keep clean.
I used to have a set of these on my coupe. They were a nice upgraded look I thought. For a coupe or sedan, with your choice of center caps to suit.
I took them off to go for the AMG Penta wheels though..
The W140 shortie SE and SD sedans are a classic sexy Body style for the W126 and handle a tad better than the W126 SEL long wheelbase sedans too.
They look even better with a set of bod color painted slim no_DOT euro bumpers that occasionally turn up in junkyards at a reasonable cost, though they disappear very fast.
as seen on a friend' Gen II 1990 coupe the day he got it in So Cal last year:
The other thing you need, is euro headlights, for a better look, and beam pattern and more brightness - it is the factory look. For the "Compleat" lok get a pair of euro headlight wipers and motors.
Again, on mine:
