G2 w/hotshoe PC adapter
It depends on the trigger voltage of the flash you are using. If you can't determine that check here:
It voltage is too high, then you can use a Wein SafeSync.
I don't remember what voltage level is safe. You can get that from the link I posted.
Can a hotshoe PC flash cord adapter be used without causing damage
to the camera? How about using w/ METZ 60ct bounce?