Do you have brass fittings?

Yes, they are all available here.

Can you tell me which fitting I need?

Rarely. Most fittings have to be matched to the existing fitting or inlet by comparing thread diameter and size. You can find the most common fittings for a particular carburetor model by looking under the carb model heading here but this is by no means an exhausting list.

Do you have gaskets for the fittings?

Yes, a large selection. Many of our fittings include the gaskets, but they can be purchased individually.GK100 is an assortment set which covers many fittings