Door Latch for 63-B Cabriolet

[dad's'cab]

I recently became the owner of my Dad's 30-31 Cabriolet. He bought it in '35, my brother has had it since the late 80's and I got hold of it several months ago and am beginning a restoration. I have most all the parts for it but am missing the driver's side door latch. These are real hard to find. Does anyone have any insight as to where I might be able to dig one up?