You should engage a CPA familiar with international taxation, especially since you seem to live abroad and are contemplating investing in foreign companies.Generally yes, a foreign corporation that holds and rents real property would be a PFIC...however a controlled foreign corporation (CFC) is statutorily excluded from being a PFIC and is subject to a different set of rules.

The only time I really checked out real estate prices was in Oslo, and I was surprised to see that they actually seemed cheaper than in San Francisco, though I know I didn't have any insight into the taxation of property in Norway.

Isn't that why you would create an company structure in the first place: reduce exposure and taxation benefits. 

However, capital gains tax, selling costs, CA tax at ordinary rates, cost of sitting cash during poor timing and perhaps most importantly, my less than stellar buying ability make it less likely I will sell the 20%... 

We will keep rental properties in an LLC.Tilmon, flipping properties inside of your IRA is considered active business and will result in UBTI taxation.

Land taxation should replace all other forms of state taxation.

The default form of LLC in LA is a "pass through entity" and all of the taxation and tax benefits pass through the LLC to you personally.  

Unlike an IRA, however, a 401k is not subject to UDFI taxation on debt-financed income.

I would see a CPA about selling it and what your taxation would be on the proceedsIf you owned it over 12 months then your taxation would be lowerSelling on land contract at 10% down or more might be a good ideaThere is a law in Ohio that says if the vendee buyer has less than 20% in the land contract and under five years in the ontract, and buyer defaults, you can evict verses foreclose.

The ROTH is an excellent way to delay taxation on gains.