I'm currently running zipmax on my MAME 0.80 rom set using 2 passes with 7zip, then bjwflate, and finally deflopt.

My questions are...

1) If time/space/memory were no option, what settings/compressors settings would (most likely) give me the best possible zip compression on my rom set?

2) I'm concerned that I might somehow make my zip files incompatible with the zlib used in MAME? Is this even possible?

...
Krick