Thanks for the link Chih-Wei! Unfortunately I rebuilt a few times with the changes to the init.sh and I am not able to enable Portrait mode. Do I need to specify the proper matrix as well? Here are my modifications in init.sh, init_hal_sensors():
has_sensors=true
set_property ro.hardware.sensors $hal_sensors
#[ "$hal_sensors" != "kdb" ] && has_sensors=true
set_property config.override_forced_orient $has_sensors
Please note that I attempted to comment out the boolean check for "kbd" as that was false (i.e the value WAS "kdb") for my case to force the setting of the property. I verified via adb shell that the config.override_forced_orient property was set to true as well. Thanks for your assistance!