Thanks, Jim.
The casing is made from a section of fence post I found down by the creek. It's a bit pitted in places. I don't think it would blue well.
Attachment 58257
Most of the original parts were indeed blued. They are from an SA marked parts kit. Picture to show the contrast with painted.
I am leaning toward paint or powder-coat over Parkerize. Maybe a crinkle like the commercial Sterling guns.