Can you, may be, re-release the demo video with different/no sound?
PM me an email address and I'll provide a direct download link.
Speaking of music: Can you digitally release the OST of the hack somehow (bandcamp or soundcloud etc.)?
That's an interesting idea, I'll let Optomon answer that one.
Last question: Will you release the MMC1 version, too? Seems like it's a completely functional hack and that it will differ from the MMC3 Version in many ways.
Most likely not, even though it was playable start to finish there was a lot of work remaining. Title Screen, sprite work, additional ASM, graphics work, it's a long list. Basically it was a play test for the level design and first round of ASM modifications, it still contained the original music so no OST.