There is no corrolation between an 11 bit ID and a 29 bit ID. They are different and unique to the manufacturer.
In the case of an 11 bit ID, the ID is typically used to describe the data bytes of the message. For example ID 0x123 might always have 8 bytes of data that have Engine Speed, Accelerator Pedal Position, and Throttle Position. And every time this message is sent it contains the same information in the same order and byte position.
In contrast, a typically 29 bit network may encode special information in the ID such as the message priority, parameter ID, and source node. This is similar in concept to the 11 bit ID except with more information about the frame.
But its important to note that just because an old model of a car has the ID 0x123, the new version that uses 29bit IDs may or may not have an ID that contains 0x123 and this frame is likely to have nothing to do with the 11 bit version of the frame.