My number would be about 560 before that.
It does not have a model number although where that normally is located in the frame, is the number 7094 5 then some smaller symbols or numbers, looks lie a small Y above the 7 and tiny 3 below it.

It has the square cylinder release.

From some other comments and what I get out of the catalog I think about 1957

the SC seems to indicate as a J frame, not an I frame.

__________________
Jeff