I loved my manual trans W115. The suspension is the same as used in the R107 (SL) from 1972-1989. The SL is a much heavier car than the W115, so the suspension is very robust for the car. The /8 is also much lighter than the w123, so power delivery is better. For the diesel, no need for a turbo to make the car drive fast enough.
If I were in Bombay I would want the simplest classic car than the most complex. If you can find a rust free manual transmission car with wind up windows and none of the bells or whistles, you will have all the power you need. The E220 is a really complicated car, and the w123 is its predecessor. As Bill said, the /8 is what turned into the w123. It was the first "E" series car. I had a drop dead simple sedan with wind up window, no AC, no Power anything. I could get it to 85mph for extended highway drives. I could also run it on most any compressible fuel, from SVO to kerosene and #2
diesel fuel. If you really had to, you could run motor oil and ATF mix without doing great damage to the injection pump or injectors.
A petrol version of the w114 is not as stout a car, since the carburetors are problematic. The engines are also a bit less robust, as they are not engineered as forgivingly as the diesels. They do run a bit faster than a diesel and have easy access to petrol, but are not very good at mileage. I was able to get from 25-28mpg in my 220d. A petrol engine will get maybe 15-18mpg.
The /8 (114/115) do have rust issues. Any 40 year old car will show some. The /8 is prone to rust at the front and rear footwells at the corners. This is due to failed windscreen shields. The front can also be due to accumulated organic matter behind the fender splash panels. I would remove the panels to see if there is some gunk and rust building there. The trunk floor can also rust from condensation and seal leakage. The spare wheel well gets a plugged weep hole and that can rust. The front air scoop drain holes can get plugged with organic matter and hold water in the firewall. The rubber flaps harden with age and can hold water before they perish and fall off. The USA cars have bad headlamps that allow water intrusion. A full glass headlamp is less prone to rusting behind the headlight bucket.
If the weep holes are all kept clear, the onset of rust and corrosion is limited. A well cared for car that parked indoors and was not driven on salted roads will be far less prone to rusting.
I liked the 220D so much I just picked up a '76 300D to play with last month. It has a whole basket case of issues, but it will be very easy to work on since it is such a simple car. I will be doing lots of rust repair, and I will be spraying the hidden areas with light motor oil to seal moisture away from the metal. Places like door rails, under the body and anywhere paint and light do not show up.