Even SCE-200 is much better than F-1 in terms of efficiency and P2W but the absolute trust of the F-1 was much more given the huge fuel consumption that's why those missions were so dam expensive. Now the main thing is chamber pressure which is similar to the pressure inside a car engine the more the pressure higher the trust.
So what India needs next is higher chamber pressure engines for main stage and then something like Ion/EMDrive for space.
EDIT: BTW India can make a Saturn V right now but given the black hole of the amount of money it will consume its better to invest in newer cheaper technology to use and make.