SAG Support confirmed that only MQMD headers are supported currently using the Adapter and its templates. I created a feature request(07077) and R&D is going to do a thorough analysis of MQ Headers available from IBM and include them in their future release.
For now, i used MQ Classes provided by IBM and created a Java service to create the MQIIH headers and LL\ZZ fields to send messages to MQ-IMS bridge. For receiving messages, i am still using the MQ Adapter listeners\listener notifications.
I did have to use the message format as “IMSVS” in the return messages.