KoKi 10000s

[Welshbloke]

I seem to be assembling a JNR container train, and have ended up with a couple of Tomix KoKi 10000s and a KoKiFu 10000 so far. A few questions though:

 

I know these were built for a higher speed than any other KoKi of the era, so would presumably have been kept together. Did they ever mix with other types of KoKi or other freight stock, or did they stay in block trains for their entire lifespan? Mine are the post-1974 version converted to handle four containers.

 

Did any trains using them run through the Kanmon Tunnel? I have a lone EF30 which I'm be tempted to find a sister for and dedicate to hauling them. I have seen photos of EF30s on container trains but couldn't make out what type the KoKis were.