I think here is the best and safe solution:
1. Clone the live site => the clone version include the same database and files : we do this step to make sure the live site have no down time
2. Override the files of beta site to the clone version : this step can make many extensions do not work so that let 's clean cache and re-index
3. Activate all of extensions and clone configuration from beta site to the new clone version: I don't think this will take a lot of time, at least change some CMS pages and admin templates will take less time to upload 900 products a lot

.
4. Finally, deploy the clone version to live version if everything is working well.
Hope it help you to solve the problem.
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