Actually I did not find one,gave up. What I did was bought a repro trapdoor 1873 one. It was of on the curvature quite a bit. I was skeptical but was able to heat it, bend, file and such and got it pretty dang close after about 6 hours of that and final fitting. Made the trapdoor. I did not want to remove wood and change the original curvature of the Whitney stock at all.
So a lot of extra work involved. I made the trapdoor. Here is a pic of the plate from the rear. You would be hard pressed to tell it was not original..Thanks for the comments.