Ok, here is everything I know about that port engine. The previous owner told me that he had both engines running fine when he first purchased the boat and was moving it back to his dock; during the trip, the port engine started coughing and making a puking sound, so he shut it off. He talked to the previous owner and found out that it had not been winterized the previous season. He also talked to someone who knew more about engines and was advised that it was most likely a cracked intake manifold. This is when I purchased the boat.
I removed the intake manifold and brought it to a welder, who told me it was cracked internally beyond repair. I then purchased a welded (but pressure tested) manifold and installed it. When it came time to try starting that engine up, I quickly discovered that the oil pan had developed a crack as well. Due to its location, I decided it would be way too much work to remove the oil pan; I repaired it with quite a few layers of JB weld slathered along the crack and I have not detected any leaks out of the pan since. Once the oil situation was resolved and we tried starting the engine, we discovered that it cranked slowly and irregularly. My thought was that was water remaining in the cylinders, and once I removed the spark plugs and cranked it, I found this to be true (This was mostly in one particular cylinder. I did write down the description of the spark plug electrodes as I removed them, and still have that description sitting around if necessary). The water in the cylinder looked like your typical water/oil mix - the telltale grey oil. Note that the engine cranks quite well with the spark plugs out; Once they are all back in, it goes back to the slow crank. Obviously this is a compression issue, but I don't know enough about engines to tell you any more than that.
At this point the engine IS assembled, and the spark plugs are currently still removed; I bought a new set but have not had a chance to put them in yet. There is NO water evident in the oil, even after cranking the engine quite a bit, so that was a good sign. My next step was of course to check the starter cable to make sure it was getting enough current; if I got it to crank well but not start, my next step was to check the fuel pressure. However, I just don't feel like the fuel has anything to do with this. That part all looks good. The spark from the distributor looks good as well.
So, there you have it. I really wish I had the time to finish troubleshooting the engine, but I simply do not. I'll see if I can find some pictures of that engine; I don't know what it will tell anyone though, as it is fully assembled and looks fine. And as I said, the starboard engine starts and runs very well.