Reencoding All Videos in Photos.app with HEVC

I have tons of older MPEG and h264 videos in Photos eating tons of space, and I'd like to batch reencode them all to use HEVC. I've trying individually "editing" (Right Click -> Edit With -> Compressor) the biggest ones with Compressor and saving the reencodes to the same directory where the originals reside, but Photos doesn't seem to detect the new file and just seems to delete it as soon as the encoding job finishes. Is there a simple process for doing this *within* Photos and Compressor that retains all timestamps and metadata? I don't want to piece together a questionable script with ffmpeg that might miss some metadata I'm not aware of.