I have 10 stripped pine doors to fix. The outer structure of the door (excluding the panels) is about 100mm. What size latch barrel do I need? There seems to be 75mm and 63mm (3" and 2 1/2" ?). I guess the aim is to put the handle in the middle of the 100mm of solid wood on the door rather than too close to the panel or too close to the edge. Anyone know how far in the hole is in the 75mm and 68mm latch versions?