FP Marauder

So I'm not sure where to go in terms of a Marauder build, but with FP getting buffed in 1.2 and having nothing to do with my Marauder, I decided that's the way I want to take things. Im lost when it comes to putting a skill tree together, if anyone could point me in a direction and or give me their two cents on the idea, it would be much appreciated.

MARAUDER LEVEL (77)
GEAR CHOICES:

--NON LEGACY KAOMS HEART-- (DONT HAVE THE CURRENCY FOR A LEGACY PIECE)

--5 LINK TARYNS SHIVER-- (FP > SPELL ECHO > FASTER CASTING > GMP > FASTER PROJECTILES)

--PYRO RING-- (I WANTED TO USE PYRO RING IN ORDER TO CONVERT MY COLD DMG TO FIRE IN ORDER TO GET KAOMS FIRE DMG BONUS, IM NOT POSITIVE IF THAT EVEN WORKS SO IF SOMEONE COULD ANSWER THAT QUESTION, WOULD BE GREAT)

So those are my gear choices thus far, if this a bad idea, I'm open to suggestions. Thx for any feedback.