The fastest Alpha I've seen had an APC 10x7 prop and a big (3" I think) plastic spinner on it. The spinner really makes a differnece because it smooths out the airflow around the nose. And like other guys here have said, your prop is your biggest problem.

Porting the engine will only do so much with out a tuned exhaust, it probibly isn't worth it, but if you want to do it, go for it. Just be sure to get some tach readings useing more reasonable props before and after.