Hi Eric, I hope you don't mind a Triumph guy jumping in on the MG board!
There is very little that can be adjusted on Weber carbs without changing internal parts, main jet, emulsion tube,air correction jet, pump jet etc. Only when these items are correct for the application will the car run properly and get reasonable gas mileage.
You probably need to take your carb apart and note down the tiny numbers on all the parts, then compare with the recommendations for your car on a website like Teglerizer or Pierce Manifolds.
A cutaway diagram of the carb is helpful, and again, can be found on the internet.
I do not have much knowledge of your carb, as my wifes Spitfire has a 40mm DCOE, but I think the principles are similar.Perhaps someone else with a similar setup to yours can give more detail.
Simon.