The permanent carburettor filter is usually included in a rebuild kit. When you remove the float and unscrew the needle valve you will find the filter, unless someone has taken it out.

I do not disagree that you had to replace the fuel filter 10 times before it stopped clogging up, but I would think it was rather the rubber hoses that clogged it. It does not make sense that rust would be able to travel down from the fuel tank and up the side of the engine. It would either gravitate down, or it will float. And as said, there is virtually no fuel flow to force it through.

When the car came out of storage, I've used it for 6 months and then had it services and prapared for transport halfway around the globe, and 3 years later I have driven a total of 20 000km on one filter. There is only some sign of dirt in the fuel filter, but it is still fine.