I assume it's FoMoCo 1250 single venturi carburetor, most commonly used on Cologne V4 (there were also Solex ones, used on early models).
I did some research when I rebuilt my carburetor. I've encountered several repair kits, as pictured below. It appears that there are several incarnations of this carburetor, and the largest gasket that goes below the top cover has three layouts. Some kits have only one gasket, some kits have all three variants. It's best to get the kit with three gaskets, unless you know which one you need and there's a kit with proper gasket (it's probably cheaper then the universal kit).






oldcars.de has this:
http://www.oldcars.de/cgi-bin/shop/shop ... 25&exact=1But not exactly the cheap one, and only one gasket layout.
Surprisingly, I've bought the most complete kit and significantly cheaper from my local carburettor spares supplier:
http://www.eter-mot.com/default.asp?kat ... pro=353751So, if available in Poland, I think it should be possible to obtain such kit from your local carb specialist shop.