Scavvies were a great gang concept because it was very open and any player could propose his own version. Your gang has a kind of Fantasy flavor in it.
For the rules, you raised two main issues : the WYSIWYG weapons rule and the lack of some classic gangs cover in the new system. Good luck with that.
That's why I think the venator gang rules would work best due to the fact you are free to choose from the trading post for weapons and armor
I don't know if Venators rules will work best, but they are the official way to go with a gang defined as Scavvies. (You could also use Chaos cultists rules, but that would mean a change of your gang fluff).
You could also use retrofitted scavvies rules to the N17+ system, but they won't be official.