I'd like to add that airflow gains at mid lift are much more important than high lift, as the valve spends most of it's time there. It's quite easy for a novice to attempt porting and actually lose hp and ruin the casting. The best things that can be done for a beginner is a good valve job (pay to have one done if you don't have the tools/experience), some light blending of the seats into the first couple inches of the port, a gasket match, and knocking down any obvious casting imperfections like flash and parting line mismatches.