As you surmised, that coffee w/alittle creamer has water in it, probably oil, perhaps some kind of engine honey and who knows what else....
As was mentioned and since you still have somewhat easy access, drop the pan after you've drained all that gunk out and inspect what you've got. The oil pump pickup screen probably needs cleaned out and if that pan hasn't been dropped in a long time it's probably got all kinds of gunk built up in the bottom. The pan on my 54 engine has 2 baffles installed to keep the oil from splashing around I rekon, and theres holes drilled towards the bottom of these baffles to allow the oil to pass through them, make sure theres no gunk building up and clogging those holes.
What you might do once you button the clean pan back up is to go and buy some cheap 10w30 oil and cycle it through the block w/your drill enough to let it clean out the passages etc. Drain and then fill w/the good stuff.
The oil in my old 216 looked alot worse than that and I turned the engine over quite a bit with it while troubleshooting it. Didn't seem to do any harm, at least no more than what the engine had going on in it after sitting 40 some odd yrs

I did flush it out w/some cheap oil then refilled w/some good stuff before I started it up tho....
Good luck
Dave