Whooooooo - off thread but very interesting.  (I hope.  Haven't looked at it yet :-}).  Should be added to useful links, I suggest? 
Good to hear you are making progress Gary.  I was about to suggest drilling the hole oversize, but David beat me to it.  I always use that method, not in the least because it's the only way I could ever get anything to more-or-less line up, because both my hand to eye co-ordination and measuring abilities leave a lot to be desired.