I save my profiles with V.Active set to 256, anything lower and the VT60 will not display an image. It does mean that each time I power on a console that I have to change V.Active from 256 > 240, but it’s become a reflex action now and doesn’t bother me 🙂 Harrumph, the reason for doing so it to expand the image vertically. If not done it will be squished on the vertical axis. Does you display not have this behaviour when you adjust V.Active?
And yeah, you can use SNES cables for N64. Like Harumph said, cable type depends on sync type.