P/S specifically prohibits forced induction, but with a genuine part number, it'd be hard to outlaw the OHC heads unless they add a clause requiring PUSHROD engines. Even so, I seriously doubt the 4.6 could compete with 500ci engines. My guess is they'll simply wuse a "small" IHRA P/S motor as many still run "Ford" in IHRA P/S.
Now taking this a step further, why couldn't they bore & stroke a 5.4 out to say 427 cubes, use the OHC heads, REALLY lighten the car & go P/S racing. There's NOTHING really "stock" about P/S anymore anyhow

so why not engineer a car most of us would consider an F/X car anyway?