Mountain Lion just input your figures into Stu Millers Calculator.
You could run with a CE Heritage (Guessing thats the same as cx?) 350 cut to 29" with a 100grain insert, or you could use the same arrow with 75 grain insert cut to 30".
It would pay to download Stu Millers calculator and play around with the figures. I had to guess a few things (centre cut, string strand count, and bow model)
http://www.heilakka.com/stumiller/ Gives you a pretty good start point at least.
Start with a longer arrow and gradually cut it down till you have something that fly's good for you.
I am far from an expert on tuning but the calculator at least lets you know you are in the ball park.
Good luck