As long as your old KS500 operates properly, it will serve you well.
In fact, when asked by friends about what type of film SLR I recommend for learning photography
I typically suggest the purchase of a camera like yours. More specifically, of the same vintage.
My logic behind this recommendation?
1. Older film SLRs of this type are relatively inexpensive to purchase on the used market.
Ebay is chock full of these older cameras (often with a nice selection of lenses), for a few hundred bucks. If the photography bug withers and dies, a ton of money is not lost to the dust collecting top shelf of a junk closet.
2. These older cameras force the would-be photographer to actually think about the results of chosen aperture and shutter speed. The difference between MAKING a photograph, and taking a SNAPSHOT, is the thought process involved prior to pushing the magic button. Along with the advent of low-cost digitals, has come a huge influx of people who will never understand anything other than Full Auto mode. Are these people making photographs? Nope! Are they taking snapshots? Yep! There is certainly more to making a photograph than just the operation of the camera of course, but learning the basics of exposure is first on the list.