Dan, you truly deserve a medal just for sending out all the PMs let alone all the thought you have put into this. My goodness!
I think the following is an answer to the adjustment problem though I am no good at posting diagrams.
Here you go...
As GB mentioned, the adjustor roller's position can vary by a considerable amount both vertically and horizontally. The fixed roller though should be the same for everyone hopefully. So, let's split your guide in half.
Packers can then be used (I'm happy to make them up and send them to you) to adjust for height. This just leaves the horizontal problem...
To fix this, enlarge the mounting holes. This enlargement along with packers will solve all adjustment problems except for at the extreme edges where grain won't get in anyway. The only extra requirement would be spring washers which we can all buy.
I'm not sure whether the above description is clear. If not, we can have a chat on the phone. (You might also have questions like, "What about the gap between the two guides?" etc.)
The main thing though Dan is don't be worried about rushing your order off tomorrow or the next day. This is not a simple problem that you have very bravely taken on. Everyone here is wrapped with what you are doing and if it takes a bit longer to perfect it, (and I'm sure that I speak for all of us), then all of us will be behind you. There is no pressure on you and even if the end result is a major disaster (which it won't be) we are all responsible and can at least have a laugh at ourselves - not you!!!
Spot and thanks,
Pat
P.S. I hope everyone is sending a few extra dollars to you.