Hi Mark,
The final version of SZ software to support the ZF7363 platform is 3.1.x. Unfortuantely this pre-dates multi-version support in SZ so your client would need to run the 3.1.x code on the SZ and all AP zones in order to provide support for the ZF7363.
You are correct about needing to manually migrate the APs from ZD code to SZ code as the older version of ZD FW predates the SZ migration utility. Unfortunately this feature starts in ZD code 9.13 but the last version of code to support ZF7363 is 9.12.
HTH,
Darrel.
Edit: A colleague runs an unofficial bulk-firware changing tool called 'Crossbreeder' this may help.
https://github.com/andreacoppini/crossbreeder