Definitely replace everything, right down to the riser. Old metal fittings and pipes in older buildings often rot from the inside, even if they appear perfectly fine from the outside. After a couple of years, the metal will rust and you'll have to tear out the new tiles.
A similar topic is well covered in the article at https://simileverse.com/when-to-clean-your-drains-and-when-to-repair-the-pipe/ . It explains in detail when pipes can still be simply cleaned, when they need to be completely replaced and the consequences of skimping on old utilities.