Luke - May have struck pay dirt. The original Ranco valve for 1947-55.1 Series is GM# 3119612, AKA Ranco Model H-11.
A bit of web searching found this reportedly
NOS Ranco H-11 offered on FBM that would fill your need to a T at a very reasonable cost!
As always be cautious when dealing with an unknown seller, but I did sign in to FB and confirmed he has a very high sales rating and lots of satisfied customers with a pretty large and varied offerings list.
Hope this is helpful. Let us know how things turn out.
