I would go for Number 2.
The Coldfire is a great project, and it could really be used in classic amigas.
Hmm. I know tha Oli_HD stated that making a new MoBo would be very difficult. But it would be cool.
Just using the already included extras, such as AC97, IDE, USB etc.
"Just" add PCI support, and stick a VGA thingy on one of those ports, some cheap GPU with P96 support.
Add Seriel and parallel ports, maybe some sort of floppy, but this can be achieved via the catweasel.
But anyway, coldfire is a great way to go with the classic stuff.