Ya, you're probably pretty close to 180hp. If your car is tuned up really good you can pull 180hp at the wheels. It will mostly depend on tweaking the SU carbs.

 

A 240Z when stock puts about 121 to 125hp on the dyno. A 280Z stock puts 135hp and a 280ZX (81-83) puts 138-145hp at the rear wheels. That is what I have seen when I go to the dyno. Of course each engine being larger will also put out more torque. The 240Z has the least amount of torque being the smallest engine. The fuel injected engines seem to kick in the torque curve faster than a carbed engine. I saw a 2.8L block with tripple webbers and headers, 9.5:1 compression lay down 151hp at the rear wheels.

My Z, with a messed up fuel pressure regulator and some intake and exhaust mods put out 135hp on the dyno. But I got things fixed up so i'm not sure how much it is now. Probably only 145-155hp with the normal intake and exahust work done.... and 194,000 miles!