150 HP LA 318 - vs - 230 HP Magnum 318

I wondered about net and gross. I didn't know LA's were ever rated net but there's a lot I don't know, and I didn't realize there was such a difference between 230 and 180.
1972 all HP went to net. In '71 the 318 was rated at 230 hp, in '72 it was 150. If you look at HP charts, a big drop in HP ratings on all engines from '71 to '72