I've often thought of trying to find one for my Aero. Was it a progressive linkage or were both carbs running all the time ?
I haven't studied the linkage arrangement on the Brazil model since the carbs I've found there seem to run around $900, I just assumed they were synchronized. I'm going with standard US carbs and am going to gang the linkage to be synchronized like I've seen before on 2 carb cars and run the choke cable to just one.
So far the biggest issue is the air cleaners which will need to be modified to fit 2 carbs so close together, unless I get some sort of modern aftermarket type which I'm loathe to do. I could get a Brazil type air cleaner but it's sort of a bulky "across the engine" arrangement. I'm leaning away from that for now.
If you look look for a head on Mercadolivre it's an "aero willys cabecote". Right now there's a junkyard dual carb 2600 engine on there but it's way overpriced. Because of expedited versus surface freight weight categories, I could've shipped 3 heads via surface cheaper than 1 due to a minimum for surface. I've been looking but unfortunately the only heads I've found recently were single carb versions, so I just paid the premium.
By the way, I was looking at your car a couple days ago and had to show it to my wife, it looks great! I also have an early '54 Lark, well, pretty much all the pieces to make one.