i have done 2 board re-shapes. the above advice is right on. when you get the glass off and start to reshape, you want to take off as little foam from the deck as possible. the foam on the deck is more dense than the foam in the rest of the board, so if you are going to change the the thickness take the foam from the bottom. if you remove the denser foam then you will get a spongy/soft board after your finished.
check out 'austin surfboards' in va beach. i dont know if they do contract glassing, but they can point you in the right direction and they do some of the sickest glassing on the east coast.