What you’ve got to do is find a source (like a laserdisc or something) that has the 81 crawl/pandown and look for star patterns. From my hours of searching through empire, there is no one shot that has the entirety of the starfield present in the crawl. It became very clear to me that they just had one giant starfield that they used for the whole movie and just filmed different parts of it at different distances for every shot. So you kind of have to go through the film looking for matching star patterns and then stitch together various parts to create the starfield present in the 81 crawl for SW.
Fortunately a huge chunk of it is right at the beginning. The starfield behind the crawl in Empire is exactly the same as that in 81 SW, but shifted a bit to the right.