For a self port job you can do small things and pick up a lot. I did my own with some supervision after each stage; First where the valve seat is pressed into the head the seat sticks out into the port, smooth that. Around the valve guide has an abrupt transition and you can smooth that, on the exhaust I semi polished it, on both ports I smoothed out the rough casting marks. After that I gasket matched the manifold...................the car picked up 6 mph at our local track. Nothing radical and I had a good valve job done at the same time. Worth doing but I bet I put 40 hrs in it, as I went slow because you can't put metal back :)

Tom