But - increasing the resolution of your VHS videos will not increased the quality, as said above, you can not add information that's not there already. If your TV is 1080, it will upscale the video anyway, probably with similar quality. If you upscale the video file, you'll just get a bigger file, but the quality may not be any better.
Correct me if I'm wrong but it seems you want to upscale the VHS quality videos to a higher resolution. Are the original (source) files from a VHS recording? If yes, then I'm not sure you can convert them to a higher resolution. That would be trying to add image data that is simply not there. You could try something like Handbrake or MPEG Streamclip (both free) just to see if that helps but I wouldn't count on it. You could also try Any DVD Converter Pro and it may allow you to upscale the video by stretching it but again not sure it will help with the quality of the video.
You could also try Instant HD from Red Giant ($99) - http/www.redgiant.com/products/all/instant-hd/ - and see if that does anything. There is a trial version available.