That's some major compression, man...
Are you sure that it is everything and is stable?
I don't like using high levels of compression as it causes more checksum errors than it is worth.
If it is a single file limit, I prefer to split the archive into chunks and ensure it is more stable for others to burst open.
There are other programmes, besides 7-zip that offer such ball-crunchingly high levels of compression (such as Ken Ward's zipper) but 7-zip is a good one.
Free and easy.
I'm not too sure about adopting it as a standard here at abandonia (whatever the extension is that yr talking about), as .zips are pretty universally accepted by Operating Systems.
Also, please be mindful of the fact that an archive needs to be able to be unzipped in Dos and/or Dosbox (so says me).
If I only used my dos machine, I'd be screwed when it came to the newer archive formats.
I only have PKunzip.exe
[ed]
I'm likin' yr enthusiam, tho, Ozzie
keep contributing!