Here goes with an analysis of whatcha got:
the list number you posted was an oem carb on a 52>53 Ford passenger car with the 223 sixbanger. The crossed-out number is actually the Ford part number. And since it was a Ford app, it originally had a thin aluminum tag under one of the bowl screw heads stamped with a number such as: b2a-9510a. It did not have the glass bowl and/or bowl spacer originally, so your pics show a very original mixer and is also clean externally!
The air horn upper flange on that mixer is bent...is that to provide some sort of clearance for the judson bonnet?...or does it appear to have been dropped? No big deal but if that mod is for the bonnet, then a replacement carb will need that also!
It has the steel accel pump cam which uses the "long" accel pump pushrod...so that setup is also correct (and easily duplicated).
The "ported" vacuum port on the side of the main body has been blocked, a blown motor must have a "sealed" carb since it's pressurized through the hat (bonnet). That judson setup is a "blow through" version correct, the carb is not mounted inna "pressurized" box?
edit: one major item I overlooked regarding your existing 1904...the choke shaft and main body on yours is what I call the "short" version and has no slot milled in the main body for the retainer wire clip for the shaft. That means the choke fast idle cam must mate with the proper "offset" throttle lever which is riveted to the throttle shaft...otherwise, you can't set the idle speed as the stop screw will not contact the fast idle cam.
That means that any replacement 1904 that ya use should be exactly like the one you have now, or else the throttle linkage won't interchange without mucho finagling! I do have both designs in my stash of buildable core parts so I can make you an exact replica of the carb you have now!
So I take it that the distributor you are running is a mechanical advance unit only, no vacuum advance?? I'm somewhat familiar with those sixbanger merc motors as I had a few 220/250 sedans from the early 70's, still have some tech lit for 'em.
I already commented on the choke actuator, if yours works fine, then it's also "correct" for that list!
The one thing I can't confirm (I have no reference to correctly match throttle body dimensions with list number, my Holley references have big gaps for some of these old Holley numbers) is the "spread" of the mounting stud/bolt holes on the cast iron throttle body. I need to know if yours measured 2-3/4" nominal center-to-center, or does it measure 3" nominal??
I have one each of the common list number 1904 mixers that are fresh and ready to go right now. I have enough parts on hand to build two more once I have ihon send me up some reconditioned main wells. All the 1904 carbs I build are run-tested on my own engine (an IH 196 fourbanger) and we guarantee you will be satisfied with what ya receive if you order from us!
Since it sounds like you want a spare for posterity...I can assemble you a fresh one, it will have a very similar surface finish as the one you have now...but I don't do "restorations" that have the classic Holley finish (and they won't cost ya in excess of $500 either!!!). It could have a brand new nos bowl on it though if that is important??
If ya wanna pursue this, I can build a replacement for ya now, then when you receive it, make the install and verify performance, then send me the other one for reconditioning. All I need to know is what main jet you have in the carb that is mounted now as that will be the starting point for the replacement.
As for parts for the judson stuff...I haven't pursued anything in the u.s. In that regard...but...I have had some back and forths with a great guy in switzerland who deals in this stuff, he's registered here on ihon after finding out we deal in 1904 carbs. Here's the link to his website which is really a nice piece of work:
home
Dude's tag is dominic clancy. Here's a link we had going a few weeks ago where we blew some smoke about the judson stuff scroll way down for the meat:
http://www.forums.IHPartsAmerica.com/electrical-tech/3036-Travelall-window-motor.html
Ya might hit up dominick about spares for the judson stuff...but since they were so popular stateside, I know someone has a stash of this schnizz around! I can remember seeing a kit for Scout 80 back in the day!
Service lit for the Holley 1904? This link will take you to the Holley service guide for that mixer as it pertained to six cylinder ihc stuff, but 98% of it is the same as your mixer!:
Holley 1904 carb, 1953 ihc - the old car manual project
I have all the Holley service guides that are currently available in re-prints, but they don't cover the 1904/1906/1908...they begin with the "2nd gen" version known as the 1920. The actual 1904 service information contained in any ihc-produced service manual was prepared by Holley and supplied to them as part of their oem-supplier contract, then ihc simply did an edit and reproduced most of what ya see in the Holley manual link.