The OS on the Z2+ and the stock Android ROM is the same, it's only the enhancements that are different.
Let us know what you want to gain by using a stock ROM (join the Android Central Community and let us know in this thread, so we can keep the discussion together), and a lot of people will be able to tell you what to do to get the functions you think you'll get from stock Android.
(In order to get stock Android for the Z2+, you'll have to find someone who's modified Google's ROM to run on the Z2+, or you'll have to learn to modify it yourself. And every time an update comes out, you'll have to do it again, because once you modify the ROM in the phone, it won't update.)