Originally Posted by
CliffordK
In the OP's case, if only the front of the frame is rebuilt, then at least the rear triangle would likely stay original which would reduce the work somewhat.
I am pretty sure the angle of the OP's downtube is going to be wrong. Maybe it can be bent into the right angle. It's a lot of work, much more work than building a new frame. With new head lugs and new head tube, it would be a bit less. Cut off the head tube by chopping the top and down tubes, hang the old headtube on the wall, and put it back together with new parts.
Good find on that Nolan frame thread. The final bike looks like it fits okay.