From the pictures, it looks like a weeping (I would hardly call it a leak) sump cover. Really, really common on these 60-yr-old-technology engines. Remember, please, that oil leaks were pretty common on all air-cooled VW beetles from several sources: The sump cover, the sump drain plug, the pushrod tubes and the non-existent "seal" behind the pulley (which was actually designed to leak a bit oil behind the crankshaft pulley). I don't see any evidence of the last two in your pics, just the sump cover, which is "sealed" with a 1/64" paper gasket which is next to useless. Everyone on here thinks my engine must be clean as a whistle but, when I pulled it a month ago it was a whole lot worse looking than your pictures!!
Aircooled.net has some nifty extra-thick silicon sump gaskets that you can more-or-less easily install with the engine in the car that will eliminate that particular leak. I just installed a pair during my current engine " freshening" because I had a similar weep, only quite a bit worse.
If that is the only oil residue you have, I would jump on that car. It'll take you (or any decent mechanic) about an hour to correct it with the proper gaskets.
Brad Penn "regular" oil is perfectly fine for these engines. If you run the "green", so-called racing oil, it has more "slippery stuff" in it, which is better, of course, but the old stuff (which is really, really good Dino oil) has a lot of the same stuff and is just fine.
Tom took good care of his car. Don't be afraid to purchase it.
gn