Chest Holsters need to have their own configuration. For now has been replacing the "Vests". A Chest Holster is not a vest, so i suggest to create a new config set of this kind of item to put it above the Vests. Or just attach it to the Vest and add 4 more slots to it.
Maybe add new variants of this item would be cool.
See the attached pics.

http://www.survivalelite.com/tactical-holster-vest

http://www.amatteroffax.com/itempagey_invid_1367317649_d_ncstar-tactical-vest-digital-camo-acu.html