I would personally send them to a Total Engine Airflow. I've been looking at they're flow numbers on their CNC TFS heads, and for the money they can't be beat. They keep a relatively small runner(185cc) and flow a ton of air(over 300cfm at .500) which means great velocity in the port. They are also very reasonable on port work since they do it in large volume. A set of ported TFS heads from them is 1800-1900 bucks, but since you have the heads I would suspect about $1000 in porting cost. I know this sounds like alot, but that's for an awesome head... Ask Jeff, he had the stage 2 ported TFS heads.