Thanks for adding to the info base on 1904 type carbs. The many variations are confounding at least.
here's a few notes from a previous thread that may not be too helpful but you may empathize:
I believe the 1904 with the SCV valve is the exception . the 1904 was used on many different vehicles from IHC' to Fords through the early sixties. I am under the belief the SCv was used on the Falcon but not most others.
The mothballed Clifford built 250 I had the good fortune to turn up, was equipped with three extremely clean rebuilt and modified 1904's with SCV's. They look great and have some interesting mods' like milled airhorn to allow standard air cleaners, removed, and filled choke shafts as well as plugged vac ports (Duraspark dizzy).
I tested each of the Clifford modded carbs individually on my stock Falcon 170 "test bed" . I was very disappointed to find only one of the Holleys ran decently. The Clifford setup used a "big" 1904 with the 1-9/16" base in center and 1-7/16" base front and rear (rear one ran good). After rebuild kits and many hours of testing I got nowhere and was frustrated.
So I got determined. I started cruising E-Bay for 1904's and found they show up regularly and there are many versions. I started picking up a few - often they go cheap but clean ones, especially glass bowl types get a good price. The great majority DO NOT have the SCV. They are categorized (App' & CFM) by the "List Number" but I've not found two the same.
I test each one on the 170. A couple ran good untouched and I'm experimenting swapping metering blocks, jets etc. with some success. I've got a few that I just can't figure out and a few running great.
I have a "typical-generic" - "small" 1904 supposedly for '53 Ford. It differs from the newer Falcon 1904's in that the Choke linkage is reversed, the accel pump cam is metal and no SCV's. :
One "big" 1-9/16" base 1904 with large venturi has a weird choke plate with integral diffuser and the fuel feed tube IS the choke shaft. (Only one I've seen):
Differences between them are mainly the base and venturi size. Some have marked main jets - most don't.
There are lots of low price carbs available. I paid less than $20 for most.
I'm convinced it's true that Carburetor is French for "Don't F%#& with it..."
Powerband 8)