Have a set on the way...should be interesting.
This 7.3 is not an in line valve head.Are you perhaps getting splayed confused with valve cant and valve rotation. Cup cylinder heads have rotated valve angles like the old Cleveland. This 7.3 head and an inline valve head like a SBC and Windsor.
If I recall correctly 'Splayed " was some sort of Chevrolet term they applied to their BB Mk IV cylinder head layout. Yoursource for your cup head description is close. Both valves are rotated off lateral centerline and then canted.I guess I'd have to see a drawing to be sure. LOL! I was told cup heads - Chevrolet and Ford have canted intake valves and rotated exhaust valves. I'm thinking canted and splayed are the same thing.
It seems like you are yelling at me, I don't know whether to be offended or not, Lol. Cleveland heads are canted aren't they?Canted valve is a compound valve angle. X and Y. The valve layout has nothing to do with the term canted. That's a rotated layout, non inline.
The 7.3 heads are inline, but canted/splayed.