I've just stumbled now (2019!?!) into your post; I was looking for details for my Gibson GA-300 amp.
The head (no speakers) is located in Italy (like me). It is fully working (well... unlike me), restored and updated (the old worn-ot parts have been saved in a plastic envelope).
Should you be still there and interested, please let me know (so we can bring back together the two -now separated- units).
tx (sorry for my indecent English)
PS - Oh yes, I forgot my reference : email@example.com