I really like Beman MFX Classic carbons. They are small diameter, very durable, & heavier than many carbons. I've had 2 dozen this year and will get another 2 dozen this winter -- I've broken only 1 but I've lost 10 or so.
I put some figures in Stu's Calculator for you.
If your bow is 50# @ 28" and your draw length is 28" but your cut your arrows to 29". If you are using 125 grain broadheads, 3, 5" feathers and if your bow's window is cut 3/16th's past center the chart says you would shoot MFX Classics in the 400 size.