It is just the Magic Barrier skill bonus that you need to be wary of, so you can edit the Larian Armour (or another breastplate) to take its place. DAD's Item Editor can also change the name of items, if you want the replacement to look more like it matches the rest of the set.
It is better to edit equipment with a bonus or two, actually. In the editor you may have 2 or 3 items with the same name, and if they have the same durability and armour/damage value, the bonuses would be the only way to tell which entry is the one in your inventory.
