I think the Olds is not the simplified version we've seen before. I'm guessing they started new considering that I remember they never released the simple one because Revell was not happy with it. Check this thread.
I've got the AMT '56 Bird floorpan, interior sides & frame under the AMT '57 body. It's been A LOT more work that I was expecting. The AMT '56 Bird is kind of craptasic kit (IMO) compared to the others they were putting out at the time. At least it provides a decent start to a conversion. I recently got to discuss with Larry Boothe the modifications he made to his killer '57 from many moons ago (rear fins are quite off). Fix the fins and it greatly improves the look of the model. I had to graft some of the '56 nose on as well since my car will be a gasser and not have the front bumper. Have fun with the dash too!
Kool. Norm's stuff is long sold out. Would like to see a scan of it if you get a moment. FWIW, if I was "starting over" on mine. I'd start with the AMT '56 and graft the '57 quarters on (after "fixing" the quarters of course). Putting all the '56 parts into the '57 body has been a lot of work... My interior will be kinda custom so thankfully I don't have to "obsess" about that.
I do not have release dates. I know that there are many sets in the works, including a '55-57 T-bird. I can say one had a part in a '70's TV show. One was an "Ace" in a dumb pet movie. Another one was a "Mr" on a 80's TV show...