So, my dual delLorto carbs are running way to rich, I'm getting lots of backfires and dieseling. Just wondering how to pare down the gasoline flow. Which screw do I turn to lean back the carbs? Any help would be much appreciated!

Sounds more like a lean condition to me.

Click to view attachmentclockwise is lean, counter clockwise is rich.

Dell tech book (which you should consider buying - written by Bob Tomlinson - see Amazon) recommends 3 full turns out from fully closed as a starting point.