No, I had left £25 on but didn’t bother going higher. Don’t know where it might have gone and besides the terminal it needed (not cheap) I didn’t know whether the diaphragm/voice coil were functional. GP1’s do come up in pairs fairly often & lend themselves more to the kind of long Western Electric style horns 12, 15a or the type Coco has (16)
I do have Vitavox as a search term on the Easy Live auction site but was surprised to see one actually pop up. Was also looking at that Telefunken R2R, less for the machine but more for the ECC83 & 81 that’d be inside it.