You could probably skip the PKZip part since it hasn't been used since the days of MS-DOS and use
FileSplitter on the PC to convert your large file into 720k chunks. Format the floppies to 720k from the Windows command prompt, use CrossDOS on the A500 to read the PC floppies, then use the
join command from the CLI on the Amiga to join the chunks together on your A500's hard drive. Then to create a real disk of your .ADF file, use
ADF2Disk.
