Blend the radii where it transitions from the port to the bowl area, then clean up the area of the bowl where it meets the seat AFTER the 3 angle valve job is performed (see pic below). Clean up and smooth any areas in the combustion chamber that are sharp-your goal is to smooth them and remove as little material as possible in the chamber-(see pic), both of which will require you to be very careful not to nick the seat area. You can also use the gasket to set your profile and raise the roof area of the exhaust port if it requires it (assuming your exhaust manifold or header matches the exhaust gasket) and then LEAVE THE REST ALONE.
Unless you're going with MPFI, do not bother to polish anything. You'll waste your time and likely make atomization worse. (when the design is already bad anyway)
Without a flow bench and experience, you'll get much better results from these small improvements than you would going hog wild porting and polishing. Good luck and have fun.
This was taken after a quick job I did many moons ago on a 258 head before I converted to a 4.0. Same rules apply.