Quality Joe skill does exactly what it says - increases quality of found loot by the particular amount. So with level 4/5 you should be getting all the loot with +70 quality.
Now for the base quality, for your level 60 character base quality is 51 - 150. And you won't ever get items better than quality 350.
The reason devs removed scavenging skill is to get around it's broken (or intended?) mechanic. Authors of this mod want for loot quality and level (common, uncommon, rare, untrarare) to scale with player level instead.