I have a 64 SG that has a Bigsby which was very poorly installed by the previous owner. I am considering replacing the Bigsby with a Gibson long vibrola to restore the SG to something close to original. I have looked around a bit for a vibrola and am a little confused by what I have found. It appears that Gibson doesn't sell them. At least I don't see them on the Gibson website. Searching ebay and reverb, I find various third party sources that appear to engrave the cover themselves. One source in Germany offers two different spring angles to account for different neck angles. Has anyone bought and installed a third party vibrola? Any source recommendations? What was the spring angle for original vibrolas in 1964? What other things should I look for?