There's a big difference between restoring old bikes and using them as donors for custom bikes. Fork ears is a perfect example. I did the restore approach on a CB350 years ago (well, the front of it anyways). I ended up with 3 pairs from which I was able to find one good set; all needed work and none were cheap.
I don't restore anything and have probably thrown some pristine collector parts in the bin because I have no plans to ever use them, and I'm not going to hold them forever. First thing to go is air boxes, followed quickly by signal lights and gauges.
Its a good thing I got rid of my 1958 BSA M21 when I did. It was a fairly complete barn find, but all I could see was a cool flat head engine, and how it would look in a chopper.
Peace & Grease, Dennis