Workprints in general are usually pointless to upscale. It’s not really because of the source medium, they are intentionally terrible quality for various reasons. You can get a good 720p or 1080p upscale of good quality VHS transfers. But almost every workprint is below even VHS quality. There are some like the Fast and the Furious workprint that isn’t intentionally made to be terrible quality because it was created for college students to edit with and experiment with putting music to a movie. But it’s still VHS quality.