|: Its 4AM here but I'm on a mission. :-D I think this is the best I can do to center them.
I would center them in a similar way. But don't listen to me, I'm always doing very rough work on my skates. I overhauled them one week ago. Now I can change the distance of my sliders to the floor quite easily. I have to do some pics of this and add them to the how-to section.
: I'm making a wooden foot so I dont drill my boot.
Nice idea. Never did it this way. Mostly used a hand-drill but nowadays I have a power-drill. Much easier, but also much easier to drill your boot with it.