Benn, a plate carrier is a vest (molle or otherwise) that carries a ballistic plate (like a SAPI). They are meant to be worn alone, or over a soft panel carrier.
Hoff, I'm all for chest-mounted pistols, but that angle is going to cause alot of problems. TT makes an adaptor that allows mounting of pouches at 45 degrees.
Another option is the BattleLab 6004 molle adaptor and a 6004 holster. I ran one of those all weekend at Irene III with great success.
Since it was mounted on a rigid platform, there was very little "slop," and it did not interfere with shouldering my rifle.
The idea is to have the pistol readily accessible for a smooth draw. The way you have it mounted, that's not possible. Just something to consider.