I was unsure about the bottom edge of the dash so I extended it into a full 180 degree radius. Also the center section of the dash did not meet with the top of the transmission tunnel so I extended that at the same time.
Boxing in the underside of the passenger side is not necessary for IVA. Gus didn't on his. All they made him do was add a piece of rubber U-trim to the return lip on the scuttle as it overhung the top rail.