When you consider that the B18B as supplied in the 1968 version of the 144S for the US market provided 115hp with a 10:1 compression ratio, split exhaust manifold (1.75" exhaust pipes) and twin SU's and "C" cam you will probably see something in the 120hp range with the mods you've made. You will have picked just a couple or 3 of cubic inches displacement and your .010" head shave will get you less than a .5 increase in compression ratio.
I originally built a performance B18 for my '68 144S using a later (carbed - Canadian?) head with 44mm intakes, some porting and shaved the head from its very low 8.5:1 (as measured by deck height and compared to specs in a Greenbook) up to over 11:1 by taking .125" off it. I also used a "K" cam. Later I moved the head and cam to a 1969 B20 and figure I have something in the 135-140 hp range. I base that figure on having calculated my speed on the Watkins Glen back straight to be 115mph (over the original 1969 B20's 103mph top speed as measured by Road & Track magazine - which I know to be true as I received a "speeder" at that figure before I moved the parts to the B20 -- pleaded not guilty - reduced to 65mph). The 1971 142E that clocked 115mph as top speed by R&T was rated at 130hp. -- Dave