Oil to rockers, need help for a friend.

Yes you can install the rocker arm shaft upside down, I am not sure about the cam bearings, I believe you can also install cam bearings incorrectly. The way I found out it was the oil galley plug was,when I spun the oil pump after pump and lifter replacement, the oil sprayed out of the distributor hole, and a similar condition was reported here on FABO. So I looked in the distributor hole and saw the plug was missing. It is also not a part that auto part stores carry, at least not where I live. Had to get it from local engine builder. I had to make my own tool to install it without pulling engine or trans, just the intake was pulled.