Yes, the Magnum plate has less relief than the LA one, and will not clamp any where near adequately on the block gasket unless it is 'modified' in a press. The OP's friend's plate could well be bent or has been deformed. It works by the spring action of the steel against the outer gasket, but it is not spring steel so if pushed too far in the center, it will deform and then not put adequate pressure on the outer gasket.
