What's your intent ? I assume it's a gravelish street
Since 15 years , assume it has caliper brakes . Typical change list :
1) drop bar/tapes etcs
2) brifter, compatible forward and rear drive
3) travel agent for brakes : not available in India
Total cost for a decent set up is about is about 22k.
Alternative 2
1) drop bar/tapes etcs
2) modified friction shifter : single speed dropbar brakes
3) travel agent for brakes : not available in India
Total cost about 5 K
There is disk alternative but too much modifications needed.
With above what you get is experience in custom bike and lot of compatibility understanding and happiness that you build something. If you like this go for it.
Else not worth, go for decent gravel and be happy.
With Regards,
R Narayan