I have learned that the 858 and the m305 are two completely different beasts. You don't really buy or use them for the same thing. The 858 is more of a cqb / service rifle / SHTF type of firearm. This rifle is short, light, quick to aim, and has 4x easily unpinnable 30 round mags. It's also more difficult to scope, making it a 5-250 yard gun I find.
The m305 is more of a shapeshifter, you can do the precision thing or the CQB. You just have to dump money into it, or tinker. Out of the box, the shorty m305 is alright, but it's no 858.
The idea is that you get both, one for a cheap blaster and the other as your scoped rifle. They're completely different things imo. I have both, but if I had to choose between the m305 and the 858 I wouldn't even hesitate to ditch the Norinco.