No, they cannot help. The current Guild company owners Cordoba Music Group only owns Guild since 2014, so they have nothing from the history. And no company would send you a label as this is like sending you a second passport without knowing who you are. How should they know for instance you did not steal the guitar and want to fake the label? This is the reason nobody would like a copy of a label. You would need to present the guitar in question together with the original sales receipt on your name to the manufacturer, assuming they would have a 50 year old label... You could maybe do this if the manufacturer would have their headquarters in Italy, but with a foreign company you would not be able to go with the guitar and the original paperwork to the factory, especially as the owners of Guild have changed many times in the last 50 years. There is no hope for this issue. You need to leave it as it is without label.
Ralf