No 396 motor would be repaired with an overbore by the factory. It's not worth the time, they would just scrap it and do it again.
The 396 to 402 was changed effective the (regular) 1970 model year, which means it went into the late 69 Camaros.
From
http://www.camaros.org/drivetrain.shtml#PadStamps
In 1970, engine application codes changed from a 2 digit to a 3 digit code by adding a prefix letter to the code. The prefix letter for passenger cars was C and the prefix letter for trucks was T. For example, the 1969 JF engine code became CJF in 1970. This change did affect late 1969 SS396 Camaros (but no other 69 Camaro model). Per the Sep-Oct 1969 Chevrolet Service News, these big-blocks with the 1970-style engine codes actually are 402 cubic inch engines. This was simply a .030 overbore of the 396 block. All advertising and sales literature still referred to the 402 engine as the 396.