Hi Christian,
Both Keith Hei and I [Branden] have 440BX boards that still run up-to-date/recent coreboot (though they do need a bit of work).
I also have an Intel 440LX board [Trigem Florida-TG (COGNAC)] that I was intending on trying to get coreboot to run on yet, but I wanted to get it reworked at the local maker/hackerspace to socket the flash chip which I haven't been able to get done.
From old messages on the mailing list, it looked like the 440BX code did run on the 440LX and I have had it run at 66MHz fsb speed on the 440BX. Though maybe the memory settings could be an issue if the ram is rated for faster than the [older] chipset can handle (I'm not sure about the details of it)?
I probably can't help much though and Keith has been working on a Haswell board recently, so I'm not sure how much time he has had to work on the older boards. I just figured I make sure to mention it at least.
Branden
PS Necroware on Youtube / scorp on Vogons forum has the same board as you [in the video: Too nice to be true? Intel i440LX was upset about my plans] and has expressed interest in open source works, so maybe he might be interested as well? I haven't tried messaging him about it.