OK. Based on the cumulative skepticism on my blowdown numbers, I went back and rechecked those timing numbers. It turns out my assistant Igor incorrectly read the dial! Below are the right numbers, and I put them in the proper order, too. I was 10 degrees off on the transfer number. So, blowdown is 20 degrees, not 30!
Exhaust Opens 104 degrees ATDC
Exhaust Closes 104 degrees BTDC
Transfer Opens 124 degrees ATDC
Transfer Closes 124 degrees BTDC
Intake Opens 71 degrees BTDC
Intake Closes 71 degrees ATDC
So, it seems like a little raising of the intake is in order. I wish I could tell how thick the remaining walls are. I am going to have to flare the intake port on the inside, as I can't make the intake snorkel much thinner than I already have. I could go even wider on the ports on the inside, but I would need to flare them. Should I just leave well enough alone in that regard? Thanks, everyone, for all the help. It has been fun learning this.
Old cat, I got those bits, and you are right - those reverse angled bits will be great for port chamfering!