disk swap on '74 or keep drums?

The noise may be from not having used them much after sitting. Could be slight rust on the drum surfaces that will quickly wear off. Same thing when disk rotors sit. Indeed, rotors are more likely to drag or slightly touch.

I sure wouldn't recommend K-H disks on a 1974 since they are rare, espensive, and wouldn't even be original. For the same price, you could install Wilwood or SSBC, and for much cheaper Scarebird, though 1973+ disks might be smartest.

10" drums are fine IMHO. 9" drums are more marginal, more from the hubs using smaller wheel bearings (at least in my 1969 Dart). My 9" drums always stopped fine and could skid the tires (not fastest way to stop). The only time they over-heated was a long drive down a gravel road in the mountains on a hot day, when the car went too fast in 2nd gear so I had to keep using the brakes on the many turns (1st was too slow). By the time I got to the bottom, the pedal went to the floor (brake fluid boiled). On normal asphalt roads, just use the engine to control the downhill speed.

If your daily driving is accelerating to 60 mph, then braking hard at a red light every 1/4 mile, you could overheat drum brakes, but that would give abyssmal mileage as some fools don't seem to understand. Otherwise, they will work fine. The federal mandate for front disks ~1974 was to stop clueless drivers from riding the brakes down mountain roads and going over the side, aka FL drivers on the Blue Ridge Parkway. Not kidding. An in-law from FL was here a few years ago w/ a rental car and after driving 3000 ft up a mountain I asked if he knew how to downshift the transmission to take the heat on the way down and he had never heard of such a thing.