it is possible, but you have to realise that some things used in fallout 1 are no longer used in fallout 2 ( for example the "roof" tiles for the masters cathedral.. ) ,so the slots they took up have either been re-used or have been replaced with " unused art "..
same thing goes for the scripts.. since script numbers have to be sequential, they kept the common ones and replaced the unused ones.. but that then means that the script for opening a door and playing the sound... is now the conversation script for someone you meet... etc.. you just need to delete all of the scripts on the old maps and replace them with new ones.....
as for the missing art, you can just extract the art from the fallout 1 dat to the relavent folders in the fallout 2 data directory, overwriting the existing ones.. this will put lots of the "unused art" back into the editor..