Getting a merger accomplished is a great success. I wish you even more success in the future by taking advantage of everybody's knowledge who was and is part of the new company.
What you did not say anything about is whose name does a new company have, or did you select a new name. If you kept one of the names that the companies had, you are sending a message to everybody. If you selected a new name you are also sending a message which essentially says we are new and we are pursuing a new path.
I do not like the word "redundancy". People who are considered "redundant" can develop feelings of inadequacy, lack of knowledge, commitment and alike. I suggest you don't use this word, especially since those that stay could feel that one of the days they will be redundant and if they are good they will look for another job.
I had a chance to run an acquired company where I came into after the acquisition. I would have done things differently, but had no choice as the acquisition was already done.
I would suggest to you to hire an outside company that has experience in organizational development and have them do for you what is needed to organize the new company and suggest the people that are needed to run the company effectively and efficiently.
Last but not least communicate to your employees as well as your customers what your plans are and keep them up to date. This will insure your customers do not leave you and your employees get the best possible understanding as to why are you doing what you are doing.
If you think the merger was tough, this is much tougher!