I have to say, I don't think PCs are capable of writing 880K floppy disks, this is a hardware thing. That said, using an Amiga floppy drive I'm not sure.
However, you've got two floppy drives if you hook one up to the 500 right? Try acquiring an old standalone version of CrossDos put that disk in one drive, than you can put the actual Amiga files(ADF is too large) on a DD (720K) PC disk and put it in the other drive. Write those to the RamDisk, or just use them from the PC disk. I'd say, writethem to the RamDisk, than copy them to a real Amiga 880K floppy. (So now you have a real Amiga disk) I myself have CrossDos 4.02a which is on a standalone disk so I know it exists.
Beyond this, isn't there something you can do with cables thats a lot easier?