Hello,
Does the Power Architecture SDK support integration with MCAL?
SDK is not autosar complaint. So I suppose such would not be possible. Also I would not recommend it, especially when MCAL is free of charge.
https://www.nxp.com/docs/en/fact-sheet/S32SDKFS.pdf
Is there an official MCAL package available for MPC5775B? If so, where can I download it?
Yes, You can find it directly at the web of the MPC5775B. As I have expressed earlier.

What is the recommended approach to integrate MCAL with EB tresos Studio for AUTOSAR compliance?
Simply install it. MCAL is only software package supported by EB tresos configuration GUI.
Not sure what you want to integrate into the GIU.
Best regards,
Peter