Besides, our current technology isn't capable of producing any of those futuristic weapons at all. Okay, the bolter, that might be possible. I believe the Russians made one similar gun, decades back. But the bullet needed time to get up to speed, so it was useless in point-blank-range. I don't know if powder has improved significantly, but there haven't been anymore tests with RPB's (rocket propelled bullets). We don't actually have a portable .75 caliber gun. You could use the .50 calibre, but that isn't possible to use on the move. Not without power armour, something that we are working on, but is far from ready. So, no Space Marines either.
A chainsword isn't possible without making it very heavy. Battery technology hasn't evolved a lot and while there are some solutions in the making (nanocarbontubes, I believe), it is still at least a decade away before it can be mass-produced and mass-used. In the meantime, you would need to have a regular chainsaw engine installed. Try wielding a chainsaw like a sword. You'll be exhausted after 10 minutes. A chainsword also has adamantine tippings, something which would mean in our world to be "diamond" tippings on the saw-blades. Powerful stuff, but nowhere near the adamantine kind.
The moment a chainsword-equivalent is developped though, I'll get one.
A chainfist is nothing but a massive-powered chainsword in a massive gauntlet. There is NOTHING on this planet that has the same raw-power output in such a small and wieldly space (except for a few kilo's of weaponized uranium). Even in the Warhammer universe, a chainfist is mounted on Terminator (or Tactical Dreadnought Armour) armour, armour that is driven by nuclear fusion (something we still haven't mastered, let alone to be used as a backpack!). So, no chainfist. Unless you mean a glove with some chains wrapped around it, but that's just a silly weapon.
So, while Warhammer is cool, it isn't for our current tech level yet and it certainly isn't available to survivors of a massive zombie-infestation. I would prefer it if we didn't "tech-up" the mod too much and if we do have artifacts, that those are limited to what our current society would be able to make. But that's up for IT to decide.