I've had a Catweasel MK3 card up for sale on the other bay for quite a while, so there is little interest in this solution.
I can't comment on yours, but there's a MK4 for sale at £145.
I certainly wouldn't be interested at that price. In fact, I only asked the original question as I have a big pile of floppies that I can't remember what's on. If it's going to cost much more than a tenner to find out, I'm more than happy for the mystery to continue.