When using the "Migrate Computers to Latest Symantec Endpoint Protection Client" it will fail with a 1063 error code. When verifying the install on the actual client machine, the actual SEP client will have installed correctly, and also will have connected to the SEP server correctly.
There are some registry tests that are incorrectly coming back in a failed state.
In the folder on the SMP, ...\Program Files\Altiris\Notification Server\NSCap\bin\Win64\X64\Symantec Endpoint Protection\Install Package\ (or x32 for 32 bit), there will be a package folder for your installation package, and inside that folder, the setup.exe file and a vbs file will be present. Edit the VBS file and change the two Wscript.Quit (1063) lines to read WScript.Quit.(0). Then save the file and run the installation again on non-SEP upgraded machines.
SMP 7.5 Upgrading SEP client