Hi , Im collecting pieces as well just as a funbuild to mess around with.
High mp throw barbs might be the most expensive build to make for barbs so far Ive tested the throw build in mp3 comfortably but I think hota or rend/cleave and ww will net better results in higher mp.
In terms of gear - a good three 300th spear with soc and higher weapon throw and spear bonus (50 % is max) is a nice off hand for the throw build.
You'l need to reduce the cost of throw by using items like a Stone of Jordan , Maras Kaleidoscope , Immortals Kings Belt , Witching hour - the max reduction needed is 9 .
With decent cc and into the fray you should have plenty of fury to spend on throws.
Looking at your character I would suggest improving vitality as well possibly even a high dps main hand 1100 ish is nice.
Echoing Fury is a good weapon with fast attacks and a socket is recommended as well.
Take a look at this Barbs profile - really great throw Barb.
Hope ive shed some light on the subject.