Why resize to 720p? What resolution are you recording to anyways? You should just leave it in SD IMO.
I have to agree (to a point).
If you could go back and capture again at a higher resolution that would probably provide the best possible result.
Upscaling to 720p may make the filtering marginally more effective, but I think that benefit would be lost by the fact the image will be scaled twice (once to 720p then again when viewing to either 1080p or 2160p).
You could turn it all on it’s head though… Capture again at highest resolution you can, run all filtering, then resize back down to SD. I know of professional restoration projects that followed that work flow for DVD releases.