I had to use the original holes the owner of the house(not the guy that wanted the gates) would not allow any further fixings. There were holes with steel bushes inserted(probably before I was born) with a 22mm - 7/8 hole at the top on the bottom it was a hole on the rock foundation so I popped in a 20mm steel ball to stop any further wear. I had made up packing plates to bring it out at the top to plumb the gates, the opening was not square. Bored and inserted threaded bushes where the hinges fit to the gate, the hinge plates that were bolted to the gate were slotted so I had height adjustment. Worked a treat.
What you talkin about it was 16 from the side I was standing at, it is a tenners worth of diesel away expensive pies!