Hmmm, gotta explain what pac files are to you guys.
Pac files are just containers for raw files that the game reads into memory.
Some of these raw files are textures, some are models, some are movesets and so on. The files that are movesets and wrestler data are compatible between console versions. Therefor extracting such a file from PS2 and injecting it on 360 will work. Files like textures and model objects (yobj) still won't work.
What I am doing is converting PAC files (containers) from PS2 format to 360 format so that movesets and other compatible stuff can be exported from a PS2-edit and used on a 360.