If your just porting for a small gain and to polish and shine it up then go for it.
You can get a small drimmel or an actualy buzz wheel and just put on a fine buffing pad that will just smooth out things rather then hone or shave anything.
If your a little affriad of using air tools on your first go.. try some emery cloth and say wd40 or pb blaster. Also you can get a really good seal by getting some valve surfacing compound.... just put a little on the tip of a valve.. then on the other side hook the valve stem to a drill and very slowly and carfully seat the valve while it is spinning.. the valve compound will help "sand" the valve groove and fit it a little better then orignal.
I don't think "opening" the exhuast port up much will help .... id just try to get the valves seating a little better.
Also if you ever are re doing and old aliminum head.. the best way to do it.. is to have a belt sander with 500 to 1000 grit paper on it. That way you know your doing the whole head at the same time and not going deeper in any areas. I love to re-surface, port and polish heads.. I dunno why.. I do a ton at school... just use your head ... go slow and remember a little does a lot... and you dont want to over do it. It's nice to have a dad that works on cars.. hehe... he should be able to help you while your doing.. (when it counts the most)