Hello,
I was able to use this program to convert GUI64.PRG to a cartridge image called GUI64.crt. I then inserted that new cartridge image into the VICE emulator and GUI64 loaded right up.
NDEFPACK
https://csdb.dk/release/?id=109269
I tried to use the cartconv program that comes with VICE, but it always complained that the PRG file was too big. NDEFPACK worked.