The old PC had the pals ladders a little offset, so that there was some complaints that you couldn't balance your front pouches as well. It also had a fastex buckle on each side for putting it on and limited adjustment. Supposedly you couldn't adjust the PC very well for smaller girthed individuals. This info is based on a thread at lightfighter.com.
I owned a new version TAG PC (just sold it on the EE), it has A LOT of adjustment ability.
The bottom of the back (hard to see in the picture) is a flap that each side of the vest with the elastic can be adjusted in or out from under the flap.
You can also use the front of the side attachments to adjust under the wings (you can see a pull tab at the bottom of the side/front of the vest), so that if you go from a coat to no coat,etc you can immediately adjust the girth, without doffing the vest.
The Eagle PC adjusts under the back tunnel of the vest with 550 cord. Many people switch it out to shock cord (VERY good idea).
Only you can answer if the vest would be off balance too much. At least I'd get a water pouch, because I would try to balance it up a little.