I don't think they'd do 180 (but am willing to be corrected). At about 150 it still had some acceleration left, but each mph above that would have been pretty hard work for such a big car. The Esprit intercooled car was only good for 180, and that had 280 hp in a smaller (if less aerodynamic, probably) shape. I worked on the driveline of these beasties for a while, terrific car and a neat engine.
Cheers
Greg Locock