The standard is 165 mm between the (rear) eyelet on the dropout and the mid-fork braze-on. That's what Tubus and others use.
thanks for your tip. Like your blog, by the way.
that's real close to where mine ended up, but not close enough, I'm afraid. Key question is: you're talking right-angle distance, right? Otherwise fork rake.....
PS: I got my measurement by taking a tape measure to a specialized dealer....