I didn't revisit the video, however, I think the 906 heads were not prepped but cut just a little to make the compression even.
i just dug up a Mopar Muscle build by Dave Young from 2012
383,built to 10.1 compression ratio
mildly ported 906 heads,comp .502/512 cam,roller rockers,victor intake
dynoed 360 hp and 380 torque
Why would Dave's engine be down 80 hp on the one Hotrod tested? Do you think it is the cam or just a different dyno?