Hello Edward,

When I put posts on the frame I brazed for David I simply welded shurt
lengths of tubing parallel to the chainstays and brazed the studs to that.

I used the same tubing as the stays and this set the distance about
right as I recall.

Look in the photo section I think there are pictures there of this. That
is where I got the method.

All the best with your project. I really enjoy riding mine

John Lewis