Has anyone used a reamer to remedy the slop in pivot pin holes on a rolling block for oversize pins and where did you begin, with the block or the hammer first and how did you align everything before you began?

The reamers aren't really the issue, those I have. More the question I am trying to figure out is how do you set everything up so the camming surface on the hammer tightens up the breach block and locks it as the hammer comes down?
Possibly I'm incorrect but this is what I believe. 
   As the hammer falls tightening up the breech block by the camming surface on the hammer this action combined with chamber pressure will force the breech block up and back slightly which causes wear towards the bottom and back of the block. Conversely as the hammer comes down its being driven under the block but it has the hammer spring also driving it up. 
  In my mind its more a question of where to begin.

What marlineguy says is true, some blocks are not square to the action. Checking the gap between the barrel and block with a feeler gauge will give an idea of how much the block needs to be built up. I made up a jig years ago for cutting the block to match the curve of the hammer. 
First thing is to make sure the pin holes are good. Last one I did I had to open the holes up .015" to come up with a round hole. I thought all the rollers had case hardened frames but found out that is not true. If your frame is case hardened you may not be able to ream the holes.