AuditoryCanvas
500+ Head-Fier
Oh wow, I was totally reading the wrong figure. Not sure if that’s good news or bad haha, now there’s another rabbit hole to fall down...Of the 57/58/64 FOTON 6N3P I have, only the '64 has a military stamp, different than the one you reference, but it also has an OTK stamp, so really can't help there.
On the heater?? Check again, 6N3P is 350mA, 6N2P is 340mA.
IIRC, MJ2 can handle up to 425mA. According to Schiit, 6BZ7 is the 'standard' tube for MJ2, which has a 400mA heater.
https://frank.pocnet.net/sheets/113/6/6N3P.pdf
https://frank.pocnet.net/sheets/112/6/6N3PE.pdf
https://frank.pocnet.net/sheets/113/6/6N2P.pdf
https://frank.pocnet.net/sheets/112/6/6N2PEV.pdf
https://frank.pocnet.net/sheets/093/6/6BZ7.pdf