Geez this one is pretty optimistic
http://www.gordon-glasgow.org/hpcalc.html.
Enter the following details and see what you get???
The Ute weighs 3600 pounds with driver in race trim.
It does 11.82 @ 113mph.
On the dyno it makes 331 hp at the tyres.
I think the "HP at rear wheels" is very close to the true flywheel horsepower.