Ive worked on many models of MB and currently own a W124 - what are you calling restoration? because if you wish to fully take it by the horns for a proper repair job with german parts. Rs 300,000/- can be enough for the job or just parts depending on how bad the car is.
When repairing the undercarriage with new bushings/mountings/shocks/GRMs/balljoints etc. expect to pay about USD 1200/- in parts only, the engine work is dependant on what engine you have.. and the expensive bit would be the interior and electrics. Some parts like the A/C blower are now NLA brand new (no longer available) - if the A/C is the climate control type and has been jugaar repaired by A/C waaley ustaads of Pakistan, prepare to shell out USD350/- for a rebuilt one, heater valve, pump and core are separate, if the vacuum pods in the dash are shot - you have to buy new MB parts, no other way around they are about USD300/- for all.
Repairing the driveshaft is mandatory too as it uses rubber couplings instead of U joints. If that coupling fails the driveshaft will completely destroy the transmission tunnel.
And you would need a very nicely laid out tool kit too with an assortment of hex bits and a set of 1/4 inch sockets and a vacuum pump tool (it is a life saver on this car), They are great cars but require some special tools to service, e.g. putting on the front crank oil seal requires a plastic sleeve, If you dont use it then it doesnt seal on the rider sleeve and you end up with leaks - problem is that you cannot see the rider as its deep in the seal cavity.
Who is going to tackle the job, you? or mechanics? and what cars have you looked at? I will quote a very famous saying about mercedes benz cars. There is no car more expensive than a cheap mercedes benz.
meaning that buy a car that is not a basket case.