~
20180204_172940 by
couerdelion2013, on Flickr[/QUOTE]
Great picture, I used a small holesaw in my drill to make the hole which is a bit neater but I didn't take any measurements. The key slot is a perfect reference point, if you could take a measurement from the top of the chrome round key slot to the centre of the push bar, it would make it very easy for future builders to get it in the perfect location. The smaller the hole, the less water will get in later.
Keep up the good work.