Bad valve job. Some of the seats are sunk into the head. Look at difference in the top angle cuts adjacent to the valves by the arrows. When you see a big top angle cut like that it's because the 45* seat the valve face rests on is sunk into the port and they needed a big top angle cut to narrow the seat. Either somebody was careless with the grinder or the head has had multiple valve jobs. It's usually the exhaust seats that are beat up from the heat, not the intake seats. I would avoid these heads if you want heads that flow at least as much air as they did when they were new.
