Al, i thought the motor in that Duster had stage V heads on it.

as for Don Little.....i'm not sure if those 9.70's were "actual" ET's, or atltitude corrected ET's.

i dont see 320-ish type flow numbers happening from OE heads without some type of welding/epoxy/port relocation.
i saw pictures of those Landy heads Hustlestuff was referring do.
VERY extensively modified.
the intake ports on those heads were reconfigured in much the same way as the Moparts Enginemasters Stage VI heads were(or rather.....the Moparts heads were reconfigured along the lines of those Landy Stage IV's).


however, i do think you could get 700hp from ported OE heads on a high effort build.
OE heads making that kind of power would certainly be rather fragile.