I was a tool & die maker and tooling engineer all my working life so used an air grinder a lot. The first link you had for the Carbon Steel burrs tells me they will not last. They are plain steel that has be carbonized so they will not wear very good. The next step up would be HSS or High Speed Steel which is what most drill bits are made from. They do titanium coat some, that is the gold color, to help them wear better. The best would be the carbide burrs.
Now, If you have never used an air grinder never never go in a counter clockwise direction with a burr. It will grab and climb and get away from you.
We hardly ever used burrs we used grinding wheels. You can dress them to any shape with a carborundum stick and they cut pretty fast and do not grab like a burr. Go to the MSC Industrial Supply Co. web site and they carry about anything you might need. There is actually a store in Greenville, S. C. I think.
If you turn the air pressure down you loose control in my opinion. It is a combination of tool, feel and experience that will get the job done. I would use a junk head to start with.
The cleveland heads do not need lots of porting, maybe exhaust but intakes too big already for bottom end power. When NASCAR ran carbs they found, on the dyno, that if you left the cutter marks from the CNC porting they do that it caused the fuel air to mix better than if smooth and gave more power. Exhaust smooth is better. Take a look at Extrude Honing the ports. As the material is forced through the passages it naturally takes away areas that obstruct. This is just one of many suppliers out there not necessarily a suggested vendor.
http://boneheadperformance.com/extrude-honing/
BMW use to do their M series heads and ports this way.
I am sure you know as a rule of thumb that inside corners in heads or runners should be larger radius and outside corners that are sharp should be made larger. But that being said you also do want the area to go from say 10 sq. in. down to 9 and back to 10. I am no expert on ports so go search the net for info for your engine. Some people spend years on a flow bench with clay modeling the ports and runners finding the best possible shape and size. Port matching is for sure a good thing to get rid of the obstructions. You will find out quick it is a dirty job unless you have an air bench to pull the cast iron away. Wear a breathing mask, ear plugs or muffs and glasses for sure. A full flip down shield is a good idea. I have this constant ringing in my ears from years of the noise in the shop.
