I would try advancing your base timing two degrees at a time (12, 14, etc.) and see how she responds. Also make sure you have a good signal to the vacuum advance and she is advancing properly. Most Mallory distributors come with adjustable vacuum advance cans. There is a screw that adjusts with an allen key through the nipple hole (where the vacuum hose goes) which adjusts your vacuum advance. I don't remember where my directions are for adjusting the vacuum advance but I'm sure Mallory's tech line could help. You may need to experiment a little bit with both ignition and carb adjustments. My base timing is set at 15* BTDC and I tweaked my vacuum advance to give me more advance under part throttle. Every engine is different as far as how much advance they need. Last but not least I assume you are setting base timing with the vacuum hose to the advance disconnected and the hose plugged.