I know this is an old thread, but I've had a few PMs about this and so I figured I would post responses here instead of limiting to PM exchange. Whoops - your inbox is full, couldn't PM you back.
Anyways, I did finish this project a while ago. I was building it for another producer and no longer have the unit.
I ended up making a mono board from an original Talkback board, and then added a blend board to mix between dry and compressed signal. I posted a picture of this board in a prior post in this thread.
The unit I built was dual mono, enclosed in a 1U rack case. I did not add any metering since the compression is so extreme. I ended up using 3811f transformers from Sowter to match the original SSL talkback card. They are about 36 £ each.
I had a few extra boards made up when I had mine made, these were sent to 2 other GroupDIY members, and I have not followed up with them to see if they were used. I believe mushy and matthew jacobs took the other proto boards, or maybe they were just looking for BOM, I forget....
I don't have any boards left, nor am I fabricating or selling any boards.
I will see what related files I can dig up. The BOM and eagle files should be in an earlier post here.
Cheers