You're not going to be able to do that in Premiere Elements. That's a very non-standard frame size, and I'm not sure how or why your digitizer is outputting video at that resolution.
The easiest and best solution is to edit this video with the software that came with the program and save Premiere Elements for video from camcorders and phones. Trying to use Premiere Elements to edit this odd video is going to just lead to headache after headache.
The other option is to download the free video converter Handbrake and see if it will convert this video to a more standard 640x480. I know that reduces the resolution a bit -- but you're working from Super 8 movies, which isn't going to give you clean, sharp high-def video anyway.
There is no 4:3 high-def video format, so trying to editing it in high-def will mean either a) a video with black bars on either side of the video frame or b) a video that fills the frame but is cropped off on the top or bottom.
(BTW, in your post you say you used "Time Stretch" to expand the video to fill your frame. I assume that's a type. Time Stretch will slow down or speed up the playback of your video. It doesn't enlarge it.)
Thanks, I thought I was going crazy!
The digitizer outputs this video using firmware. There was no software included with the digitizer.
I used Time Stretch to slow down the frame rate to normal for 8mm.
I guess I'll have to live with the bars. The mfr seemed to indicate that it was no big deal to modify the file.
Normally I would just slow down the playback with VLC but that doesn't help with uploading to Facebook.
I just realized that I could play back the file in VLC at 60% speed and use it's record button. Good enough!