You can blend in the throat area below the valve seats, but do not go too deep, you will hit into the water jackets. Just blend it in. There is great risk if you are not familar w/these heads.
You want the area below the machined portion pulled back a bit & as the A/F goes through the throat area that area will be the tightest, like a venturi, then open up wider @ the valve angles.

Not good @ explaining, but hope it makes sense, easier for me to show in person.

On the short turn radius, just blend it into a nice radius, do not worry about the gaps. No sharp edges. I use a piece of emery/cloth sandpaper, tear into 1/2 to 3/4" strips, longer strips makes it easier to hold & work faster, feed one end into the exhaust port & the other end comes out of the combustion chamber, hold both ends of the sandpaper & work it back & forth.
Gets the areas you cannot reach w/a conventional porting tool.
Example of sandpaper to get.
http://compare.ebay.com/like/230769942302?var=lv<yp=AllFixedPriceItemTypes&var=sbar

You can lay back the chamber wall a bit on the intake side on the spark plug side to increase airflow. Only have a pic of my different cyl head though. Also, you will loose some compression.



You can also knotch the tops of the cyl bores to help w/airflow.

Edges on the combustion chambers? Just break the sharp edges w/a cartridge roll or a carbide cutter.

How much compresssion are you going to run?


MBHD

12 port SDS EFI