how much horsepower from my 318?

I googled the 86 316 2v hp rating "200" hp.rating at the crank If its 200 at the crank he could add say 40 hp for the 4v and headers to make 240 less 20 percent for drive line drag which should come out to about 190. Then subtract horsepower for the pistons way down in the hole making the cr a lot less than advertised plus some hp for poor quality control equals about 175. Just out of curiousity guys, when did they start rating hp at the wheels?