That 1404 looks interesting as a possible scan doubler for an Amiga, but the specs show two possible problems.
1. finding a proper cable to go from the Amiga 23 pin RGB output to the 1404's component RGB inputs (unless you are talented enough to make one yourself, which I am not).
2. the minimum RGB resolution input accepted by the 1404 is listed at 720 x 525. I think this would pose a problem for some Amiga programs and games which open their own screens at fixed resolutions less than those numbers.