Good morning;
This theme is still relevant. Yes, if you have found an old camera, and also discovered an exposed or partially exposed roll of Kodachrome in it (check and record the ASA setting on the camera before you change it), then just putting the Kodachrome into a black and white developer does make sense. Yes, using a lower ASA setting for your light meter would help with finishing the rest of this now venerable film, if you wish to do that. If you do that, work the film advance system slowly. The film may be brittle and could crack if treated like a more recently manufactured roll of film.
That ASA setting on the camera might also help in identifying the film that is inside an unopened camera. If the camera is from the 1980s and earlier, then an ASA setting of 25 could well indicate KM-135 Kodachrome II. ASA 64 could be KX-135 Kodachrome-X. ASA 12 or even ASA 10 would be the original Kodachrome from the 1950s and earlier.
In any case, with an older camera, take a look at it before you open it. If the film frame counter has a number on it, and the rewind knob rotates as you work the shutter cocking and film advance lever, there probably is some film inside it that will have some genuine surprises on the film when you can get it processed. That ASA number will help in identifying a more limited range of possible films that could be in the camera. Yes, it can be processed, and you will be surprised at what can be done to enhance and bring out the detail in such a venerable photographic image. Once processed, and then also scanned on a good film scanner -- not just a flat bed scanner -- the photographic image programs available today can do some real wonders with negatives that many would consider to be unprintable.
"Found Film" is a real treasure. Finding an old folding camera with 127 or 620 film in it, and then processing it and finding images of men wearing military uniforms and women with "period hair styles" standing by "vintage" cars, really does bring some history directly to you. If you are lucky and the license plate on the car is visible, you might even find the people or their family.
Enjoy;
Ralph
Latte Land, Washington