My buddy has a 1981 Datsun, but he has No idea how much Bhp it had stock.....anyone know?

The base horsepower stat should be located inside the engine compartment on the passenger side firewall -- it is a silver riveted-on plate with black lettering that should state the horsepower -- if I recall it is 150 bhp -- even though most 280ZX's are about 160-170 depending on how you have the timing set -- advancing the timing gives a considerable increase in HP depending on how far you can advance it before it starts to ping/detonate.
Have fun.
Brandon

And if you took it to a dyno you should get about 145hp if everything is tuned up really good. You can add 15hp by opening up the intake and exhaust. (complete, not just a filter and new muffler)

170hp net at the flywheel if the engine is out of the car.

These cars also have about 160 pound of torque at 3000 rpm so your power band is very long and you have good power from right off the line. They seem much faster than the horsepower number shows.

An 81 non turbo puts out 135 hp while a turbo puts out 180hp!

dude, you know freakin everything about z cars and you rock for it, hey, i've seen you'r site too, you need more pics of the fairlady though