first a correction
W124 which came as yellow cab in 1992-3 was 300D means 3000 cc diesel
Now if its garaged for approx 14 years then you'll need to spend A LOT on it on repairs once the car hits the road things will start coming up... now a normal (full cutom paid) 300D W124 (with half life done as u said but not in reality) is available in Khi Market for around 1.2-1.3m max
Negative points for this car are
its been garaged for such a long time (in my opinion which is worse then driving the car on road for same time)
its yellow cab means regd under PG series i.e. whenever you are using that car as private on road. our dear tullas will take some out of ur pocket
so based on all the above. I'd say get the car between 5-6 lack. now its ur money & your purchase so if you want then u can pay 8 for the same as per your offer but since you asked for suggestions so here's my 2 cents