Just a quick tip, which seems like a no brainer now. Our lovely friend spikeybike was wrenching on a GL1200 engine in my garage when he accidentally dropped a toothed lock washer down into the engine w/ no hope of finding it (GL1200's don't have oil pans). Well, we tried to get it out to no avail. After he left, I got to thinkin' about how I could get the washer to fall to where the oil scavenge pump was at the back of the engine. Well, a little compressed air and rocking the engine and it almost shot out the back of the engine. I was able to grab it w/ a pick.
So, how to relate this to an SOHC, well if you ever drop a washer down the engine and don't want to tear it apart, try shooting compressed air down the engine to help it find its way down to the oil pan.