If you can find a radiator repair shop they should be able to clean it out for you and give it a pressure check at the same time.
You could remove the fuel gauge sender and peer into the tank to see how bad it is. Although removing the securing screws may be a challenge
As Brownbaker suggests check the fuel hoses and give them a clean out. I'm lazy and use an airline between tank and the connection to the fuel pump and into a collection bottle Amazing how much crud comes out!
A fuel filter is a must, my preference is for an inline type between pump and carb. Nothing special just a throwaway one which is changed every year as part of the service.
If you have the Weber DCD/DGV twin choke downdraught, there may also be a mesh filter on the fuel inlet. This may need a clean as well.
Arwyn
