If you know exactly what you dropped down there, my first suggestion would be to get one of those telescoping magnetic things and stick it down the chain area and try to fish it out. I dropped one of those down there once, but I had a magnet on hand and was able to grab it easily, it just sat up in the chain over the crank sprocket there. I doubt those bolts are small enough to just drop into the oil pan from up top without help. Whatever you do, DO NOT TURN OVER THE MOTOR. If you can't fish it out, or If you aren't sure exactly what is down there, removing the oil pans and the front cover is the only/best way to know for sure it is out. The upper oil pan and front cover are an absolute bitch, BTW, especially without the right tools.