The WS-420 is a half din height and conventional width. looking at the HSE, it might be half din height, could not find specs, but it is not as wide so would leave a gap on the width.
So looks like you could do it. But would probably have to do a bit of trim work and make some sort of plate to center the hse and fill in the sides.
Would be pretty cool and should not be too hard to fab up but will take some work.