Another thing to consider is whether you do indeed actually have to deinterlace at all. The answer is probably yes, but I do try to have a kind of an archivist's or museum curator's approach to this kind of thing and not alter the source more than necessary. If you have equipment you can watch the material on that can display interlaced fields as the source intended then you can avoid having to deinterlace or even necessarily upscale anything at all. Realistically though I'd imagine you'd want to watch this on equipment that will only display progressive frames and if you don't like the comb's teeth effect you'd want to deinterlace. Scaling, whether software or hardware is again another question mark depending on how you'd want to watch these when you watch them. Ultimately you'd probably watch on a higher resolution device than the TVs VHS was intended for and likely physically larger as well so upscaling would be understandable, but still worth considering if you can skip altogether.