If you already have everything apart and can get it done cheap, go ahead. It won't hurt anything. also port matching on intake is not neccisary it is better to have a step (the manifold side slightly smaller.
When air moves through the manifold towards the valve and the valve slams shut the air compresses and pushes back up towards the manifold just a bit before the valve opens again and the piston pulls the air back into the cylendar. The small step causes some resistance to this backflow making giving a better fluid dynamic to the overall airflow. It may seem insignificant, but that tiny difference multiplied by 1000s of RPMs over however long you drive adds up. a more efficient engine is ALWAYS better weather you are going for power gains, or MPG gains.