Hi CP1,
As per my understanding, there won't be changes to the SRX device either than the OS during its upgrade. So, you will not have to worry about the existing configuration already managed by the Security Director. Also, the management of Junos software is not directly handled via Security Director.
Just before you proceed, refer to the below KB. It might be useful:
https://kb.juniper.net/InfoCenter/index?page=content&id=KB34945&actp=METADATA
Hope this helps 🙂
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Kudos are always appreciated 🙂