From why I know, which may be incorrect is they take stock rockers. That should be the first clue they are going to be airflow limited, just like every other head made like it.
AFAIK they are still 18* valve angle. Valves have not been moved.
Ports are not raised and who knows if the put the stands in the correct location because you'd need to run the exact same cam and rockers as they tell you or they need to be corrected.
I don't know why in THE hell no one just makes a simple copy of the W-2 in aluminum. The market is flooded with these limited castings. Or better yet, make the W-5 head again, and fix the **** core boxes.
Then you have a head capable of feeding 390-400 inches to about 7200 and make power.