There is nothing to Zarjaz beyond a cover, and The Dredd Comic, while most of the contents are known the cover is not, and there seems to be a main Dredd story not known either. Probably easily segued into 2000 AD.
Alternity and Earthside 8 are different, they were actually 'published', probably 100 printed of each for a focus group, and pulped on return. There is only a handful out there.