I don't know anything about Z-M products, but I do know a nice looking retro project when I see one.
-----looking good, Fin!!
I don't own a throw-back/retro AR, but had a chance to handle an original, genuine M16A1 recently, and I will say the overall engineering and ergonomics were amazing.
Seeing yours - and those like them - its no wonder there is a resurgence of retro builds going on