Exporting for MP4 3D VR

I have a small file I am trying to render to an MP4 for playback. I prepared this rather high res to tes how much quality I could get off of a title with a CG in a stereo VR 360 version. I have completed a PNG sequence for this and have set the cameras correctly. The 3D 360 stills look amazing in VR goggles but I am having a terrible time getting them to translate to a moving MP4 that is needed for goggles.

My problem is that if I combine the sequence in Blender and try to render out as ffmpeg video at H.264 It will play back from Blender. But once I get the file into Quicktime, it is basically blackā€¦no image. I can put the PNG sequence in Quicktime 7 and export but I lose the resolution in the end and I have no way of readjusting the resolution. It is quite high at 8640 x 2160. I am running out of options for how to recombine these images either in Blender or out to come up with a final full resolution MP4. Any suggestions?

Hi. This post covers a youtube centric result but could help elsewhere too:

Thanks, I will give that a try