Well, if you know how to do portwork you could do a port and polish job, and also port match the intake manifold to the heads. All this will cost is your time and some grinding stones.
DISCLAIMER if you dont know what you are doing when porting you could screw things up majorly, and actually reduce performance. Port matching the intake manifold to the heads is not too hard and will help airflow, there has been a little bit of talk about this recently, there was no consensus about gains, but it seemed to be beneficial. I will be doing a port match when I put my phenolic resin spacers on.