You can check the cam by rotating it with the sprocket bolt. It should turn with little "jumps" as the lobes pass the bucket followers, indicating that it will free-wheel in between valve events. If it turns only stiffly, or not at all, it's seized. That said, it would be unusual for the B230's to do this, as they usually have an enlarged oil cross-over in the block from the number two exhaust side head bolt. The earlier engines used the gasket passageway only, and infrequent oil changes coupled with an overheat cause the sludge to block the passage in the gasket. If you see oil in the wells in the head, and lots of liquid oil around the cam, the passage is not blocked. Old belts can loose several teeth in a row, and all you have to do is install a new one.