I have a mild 1776, and here are the specs for the carb:

Stock Solex 34 PICT-3 carb. Idle jet = 65. Main jet = 132.5.

The engine runs fantastic (when I'm not having ignition related issues), and I just had the spark plugs out yesterday. They looked perfect. The 30/31 is a slightly different carb, so your numbers may vary.

Lee
Tustin, CA