Re: D0VE-A 429 Head Porting...
LOL! 20 CCs. I think it might be a bit shy of that. This is for a 4300 lb wagon with a highway gear and an RV cam, so no, getting 10.5:1 compression really wasn't a concern. The heads were shaved .010 previously, and the pistons are stock '78 so I should hit about 9.0-9.5:1 which is what I was looking to get. Aside from that, you pretty much described everything that I already did.
Removing the sharp edges as well as polishing the combustion chambers is exactly what I did ... to help reduce concerns of pre-ignition. And, then I did unshroud them. That was where I blended the chamber into the seat. Right at the seat I had to leave a bit of ridge to avoid hitting the seat or creating an shallow area right at the valve that would disrupt flow.
On the intake port I blended the hard corner just inside the port past the intake. I also opened the port to allow the intake to flow into the port without any hard edges disrupting the flow and then blended it in about 2.5". At the valve side of the port I cleaned up the casting blending in about the first 1.5"-2".
The smog hump is long gone and blended into the rest of the port prior to polishing. My goal wasn't to enlarge the port as it was to smooth and blend. The bottom of the exhaust port was blended at the turns and polished, but otherwise left alone. The top of the port received the bulk of the work. The port opening was left basically as cast as far as size goes. One thing I did do was eliminate shrouding of the valve in the port where the seats. When the seats were installed, they left a ridge roughly 1/32" all the way around. This was blended into the seat.
Brass sleeves were already installed, so no worries there.