@ Thomas
I have recently returned to the Amiga after a long absence and I found a tool called FormatZIP in my C: directory. I tried it on a ZIP that was originally formatted for Amiga, and it works. It writes the MBR. It is by Alexander Feigl.
I copied a whole lot of mods onto the disk, and besides the 8 x 3 file name truncation the files played fine on my PC.
Its very quick too.