Thank you Salal Bhai for your detailed response.
Starting from engine. You are right it was in a bad condition after running thought out on cng from last 2.5 years but now I'm running it on petrol from few weeks. Last month some work has been done on engine such as timing belt, valve and throttle body cleanedaround, 18k were spent. But still it some more things to be done which our mechanic has quoted for 9-10k. Good thing is engine swapping is not required.
Body has a major dent on right side pillar. Both bumpers required repaint. Truck has a litte dent and lots of scratches around body which can be minimized by some serious detailing work. Rear lights are broken while front needs buffing. All thses things are under 15-16k.
Suspension thankfully are much better than i was thinking. Only rubber parts like Bush and boots are required. All four shocks are working good.
After these things interior also need to be deal like seats restoration, power windows, speakers and etc around 15k-20k
Here's the complete list