Re:
As above, I’d go for the bar-end route. I’ve tried both, and flat bars are much cheaper, and way less hassle than going drops and then having to change virtually everything.
Drop bar for touring is popular in English speaking countries, I believe an inheritance from the 70’s British “touring” bikes, which were just road bikes with practical stuff like racks and mudguards. However, in Continental Europe, drop bars are the exception, and most people tour with flat bars or “butterfly” bars. Sure, not as aerodynamic (who cares if you are riding at 15 km/h with 4 big square boxes hanging from your frame) and slightly less hand positions (not so much if using butterfly bars). Everything else is to the advantage of flat bars: cheaper everything (shifters, grips, brake levers…), easier to find parts, less incompatibility problems (road vs mtb components don’t always mix and match well), etc.
In conclusion, go with flat bars, add bar ends, and if you want extra comfort, get some Ergon grips (or similar from cheaper brands) and a higher & shorter stem to adapt your geometry to touring position, plenty of models to choose from brands like Ergotec, they look goofy but are super-comfy. Early 90’s bikes are known for very long top tubes, even longer stems, and relatively low and narrow bars, not the best for long hours in the saddle.