I don't have an ADC K8C, but the K8 (which I do have) is surprisingly good for a bottom-of-the-K-line model. I'll risk repeating myself: Pritchard's basic design scaled up (to the ZLM) and down (QLM 30) equally well, using the same basic materials, so even the cheapies sound decent, though they don't have the finesse of the top models. ADC made some nice finesse-y conicals, but they're all too compliant for best results in the SL-1200 arm, in my opinion.
The K8 styli (there are three: K8, K8C and K8E) were made in the US, then Japan. Specs are similar: recommended starting VTF would be 2.0 to 2.5g. They're not expensive, originals are still available, and the bright-blue trimmed K bodies are easy to spot on auction sites. The K8C's plastic bits are a dark gray-green for some reason and the magnet is flat, not channeled. Avoid the blue K8 made in Japan-- hard to fathom, but it's simply not made as well.
Caveat: you may spot the RC398-DP combination of ADC headshell and K8C cartridge. It looks good at first glance, and it will sound good, but then you spot where the cartridge body's mounting holes are, far forward of normal, making the special RC398 headshell mandatory. In other words, you have to use it pretty much as-is. No ability to try different alignments. The stylus, however, can be used on any low-inductance XLM-style body, and the headshell is also usable with other cartridges.