Nicks Garage 383 build

Nicks got his own fancy new seat and guide machine……seems like if the valve job is a problem……is that something he did?

Does anyone have an accurate account of what the numbers are in the video for this 383?

If it’s like 340hp, that’s about the same hp/ci as a 400hp 446.
Hasn’t there been at least one stock intake single 4bbl, exhaust manifold equipped 446 that made around 400hp at his shop?
Maybe the one a couple years ago out of the purple 70 gtx?
I've only skimmed through them, but it seems he can't figure out why it won't get over 400 lbs-ft and since there factory rated for around 425 lbs-ft he think something up.