Kyle,

Don't Webers have sealed ball bearings on their throttle shafts? Are you sure it's leaking there?

If so, there is nothing you can do to make the car run decently with that problem going on. You can't tune around it. It's no different with SUs. You can cause damage by running it that way -- sounds like your rings are on the way out, but no holes in the pistons... yet. Rings are a lot cheaper than pistons. Keep running it way lean, and you will have holes in the pistons.

Sounds obvious, but a lot of people insist on not doing it: Always fix what you already know is wrong before going to a lot of trouble looking for more problems. If you know the carb is bad, you need to fix that before you do anything else.