Okay, new missing 7z is up:
Contains missing files for both x86fre & x86chk, taken from the fre/chk ISOs.
Base edition is enterprise for both (since chk is only available in enterprise edition I figured I'd use it for fre as well), so you'll probably need to use enterprise CD-key.
Files that weren't available in any win2003 iso (msn6.exe, and other client stuff) were taken from XP SP1 (afaik the missing-v8.7z took these files from XP RTM, so the files in here should be a little newer, and closer to win2003's versions)
PDBs inside symbols folder are mostly taken from win2003 symbols packs except a few files that came from XP SP1, haven't checked if all the symbols actually match up with all the binaries yet though.
I haven't tested all editions yet, would appreciate anyone trying them out. (maybe this can help solve the chk login assert?)
In case anyone cares, order of ISOs used to obtain the files:
(x86chk only) Win2003 Enterprise x86chk
(x86chk only) WinXP SP1 Pro x86chk
Win2003 Enterprise x86fre
Win2003 Datacenter x86fre
Win2003 Standard x86fre
Win2003 Webserver x86fre
Win2003 SBS x86fre
WinXP SP1 Pro x86fre
WinXP SP1 Home x86fre
WinXP x64 Pro amd64fre (for srv_info.chm)