I feel like I should mention that the map header conversion tool was built for the sole purpose of being able to view H2V maps with Xbox tools like DotHalo. It doesn't convert maps into something playable. As far as I know, nothing on the level of Arsenic (which is a H:CE to H:Xbox conversion tool) exists for H2. Halo 2 Xbox itself, though, has a ton of modding tools which makes meaningful bsp editing possible, so from what I've seen it might be possible to effectively "port" a map from H2V to H2X with the right assets and knowledge. Be warned, though, there isn't an easy "one-click" solution for what you're asking.
That's the extent of my knowledge. You're better off asking someone like Twinreaper/Kills Alone/legitimate H2V mappers for anything specific, people with experience. If you need help finding specific tools for H2V or H2X, ask in here or PM me.