You don't need to increase jet size, you need to get your timing where it belongs. About 14- is enough for a stock engine. You can dump all the fuel in it you want but you don't have a "lean" condition. You have too much timing. I had a 10 to 1 360 I built 8 years ago or so and I tried that. Didn't work, ran way better and quicker with 32-34 total timing. Actually picked up a half second when I dropped below 36 degrees. I couldn't believe it. It pinged as well but was far from being lean.