I can't think of a really good answer for you, but here's some stuff you could do:
Go to maws and look at the latest roms that were changed by version, like 0.123. You can then go directly to those individual roms and get a listing of the files needed. If your zips have the same files, then you're at least at that level.
Otherwise, I think clrmamepro is probably your best answer.
If you can locate some .dat files for various versions, clrmame pro can rebuild the set for you. If you can rebuild it and get the same set as you've already got, then you know. If clrmame pro complains that you're missing file xyz, then you can start tracking down when that file was added and get a baseline for your version #. I think it'll be quite a bit of work either way.