Very few drop bar 26er conversions look good. Like very few.
The c&v forum has a years long thread on this very topic and for every 1 good looking 26er drop conversion there are 5 goofy looking conversions due to geometry(or the person not having the correct size frame).
Old rigid mtbs can be good starting points or they can be terrible- there is a wide range due to the geometry changes taking place in the 80s and 90s. Some will have very long top tubes and a low front end which creates all sorts of fit challenges.
Shaow bottom bracket drop of older rigid mtbs also isnt what I want in a gravel bike. I want to sit in it vs atop it and a larger bb drop helps make thst happen.
Personally I wouldnt care about brakes too much. Good canti brakes with new pads can work fine. Or v brakes will work too if you just buy travel agent converters and install on each brake. Disc really isn't needed. It's nice, but hardly needed.
I converted an early 90s hybrid to a drop bar gravel bile and my brother in law did the same with an early 90s Trek 750. You get 700c wheels, older frame styling, lower cost, less wonky geometry, etc etc. Pretty much the best of all worlds.