The other option is if you can find just the images with no text like Commander Courage said, then you can put the text on so its consistant. Though if your having trouble finding high res versions of the posters this might be tough. I did notice that there is the episode I poster with no text on his website, but unfortunatly i couldnt find any of the other star wars posters on his site and i dont know if that is high enough resolution.
I think someone here had some high res images and some of the posters without text. You could use the Special Edition posters as well for the OT that would keep the naming consitant with the PT if you want that and its still his artwork...i would just at minimum remove the Special Edition from the top of the poster.
Me personally, Im still trying to decide what images I want to use when I finalize my cases for the OT. I like the set i currently have, some of the classic SW pictures for each movie, but there is so much good artwork (i like the faces set as well, and that seems appropriate as its the laserdisc source for most of the projects) and my current plan is to put all versions i have (TR47, DrGonzo, and the new releases) in one 4 pack case thats only slightly bigger than a normal case. that of course is presuming i only end up with 4 versions which is quickly starting to look like it wont be the case.
-Darth Simon