Next week I have to roll with two Red Weapon changing 60 fps to 120 fps interchangeably and I record sound reference.
They want the camera files have the TC in with the Time of Day.
Everything would work if I put my Tentacle at 30 fps and both cameras in Time of Day mode and external code?
it should work if you set the tentacle frame rate to match the cameras project time base. Then proceed like you said, set cameras to TOD and external timecode. When the TC symbol in the RED Display lights up green, everything is ok.
But please keep in mind: When syncing audio and video in post they will be in sync only at the beginning of each clip. After a few second audio and video will drift. To compensate this you have to slow down the audio by the same amount as the slo-mo of the video.