Its probably the end point of the chest that needs adjusting. Open the Joint Parameters window, select the armor's chest and select "center". The display will now show a pair of cross hairs. The green ones should be correct because you have used an existing CR2 but you may need to alter the red end point. Try setting X to zero and in a side view drag the end point up to about his ear.
If you would like to send me the files as they now stand I will by all means be happy to look at them. (Please use philc_designs@yahoo.com)