The thing that makes the slant six so desirable for a turbo project is its unusual infrasucture... its unusually thick castings and rigid archetecture.
This Aussie "Hemi" engine may well be a much better breathing normally-aspirated engine, BUT will it stand the hellish amounts of boost that would make for a 600-hp slant six workable?
Nobody SO FAR has built a 600 HP turbocharged slant six, (that I know of) but I haven't seen anybody try and fail.
That 600 number may just be a possibility with 40 pounds of boost, a BIG turbo and somebody with s lot of money...
I'm waiting... might take alcohol to do it, but I'd bet it's feasible!