Our local machine shop does everything we need to have done to build an IT head EXCEPT port matching. So, I have been practicing the art of "DIY port matching" on an old cylinder head and feel pretty confident that I can do this myself. But, I do have a couple questions . . .

How smooth does the finish need to be where I have cut away the material? My understanding is that the intake needs to be pretty smooth, and that the exhaust is not quite as important. Thoughts?

How does one cross the line between "port matching" and "polishing?"

Is there anything else I need to be worried about with this modification?

Thanks!