Great find - good luck on the build.
Just out of interest how are you going treat the rust of the frame? I have acquired a similar condition bike recently and it has the same type of rust. I have been trying a bit of T-Cut which seems to work on the smaller bits of rust, but wondered if you had any tricks for the larger bits like around the head tube.
Also will you be trying to get the rust of the components/quick releases as well? If so what will you use? Wet and Dry??
Sorry for all the questions, just trying to get ideas.