A neat and clever achievement.
When digital first came on the scene, we all wished for a conversion like this. Many entrepreneurs failed, generally because the electronics necessary to do a decent job couldn't be fitted into the space of a 35mm film.
Now the electronics can be made small enough to fit into the space of a 35mm film, we have all moved on.
Even so, if someone produced this ready made I would be tempted to give it a go. It would never be good enough or convenient enough to replace my current system, but could be fun to play with now and then. I have several Nikon F801 bodies and a couple of housings sitting about that could be dusted off.