Hey, there was no Premiere option that I could find, but I found a solution regardless.
Render from PI in 720×480. Load the video into VirtualDub, go to Video > Compression, and choose DivX 6 codec (You should have it), then configure. In the far right tab, tell it to resize with width 720, and save as an AVI. The new AVI loads into Premiere with the right aspect ratio, but a slightly smaller resolution size, even though the clip and the project res are the same. Just use the effect controls to scale the image to the right size.
I hope this helps whoever else runs into this problem.