When I did an international-to-international transit in PVG on FM/MU J class with both flights in Terminal 1 I used the No36 Lounge. You take an immediate right turn after security and go up an escalator. Not the best lounge in MU's hub: no outside view, minimal food/drink but there is the all-important shower (ask at reception).
However, if you are departing from the T1 Satellite or you have plenty of time during your transit then there is a much better MU lounge - others will correct me but it might be called No137 lounge. I used this on my most recent international-international transit as I was into T1 and out of T1S.
There're some threads that might help:
New China Eastern Lounge/Terminal?
Shanghai Pudong Terminal 1 SkyTeam lounge access for Flying Blue?