Another way to search:

source:tumblr*1280 width:1280 status:active order:id date:>2012-12-31

I'm doing it in reverse order now to take care of the oldest stuff first and give users a chance to replace their newer uploads.

abadbird said:
An issue reuploaders will run into quickly is an accumulation of width:1280 or height:1920 posts that have the same resolution as their _raw Tumblr counterparts. How can someone mark those posts so that anyone attempting this "project" can remove them from search results or otherwise skip them?

One way would be to edit the source and just put "raw" instead of "1280". However, these images appear to have different hashes than their identical counterparts so I'm not sure if we want to do that yet.