I'm interested if enyone knows iif it is possible to export what was first done as an DV PAL project to some bigger format? All the orriginal materials are big and it shouldn't be any problem to use it in 2k or HD project but postproduction was originally done as DV PAL.
This sounds like you are hoping it would only take a magic button to make it happen, which is slightly naive (no offense), meaning, no, there is no such thing. If you want the full quality back, you will have to walk the full mile in post again. That doesn't say you cannot work based on the existing project, but short of e.g. using the scale comps script that comes with AE and rigging up a few expressions to auto-size, this will still require a lot of manual work. Effects values will simply require to be adjusted to retain the look (obviously, a 3px blur will not do much at HD when it notably softens at smaller res) and working at the larger res may reveal imperfections that didn't matter before. Even things like type looking different at different sizes will require manual intervention....
Why are you not able to rebuild the project using the original "big" source files?
What is "big"?
Open a "big" Comp within the original "small" AEFX project and copy in your original maybe?