@Amit M. - That's all excellent info, thank you!
There are a couple extenuating circumstances too - I'm actually helping my partner out buying his first place, so there is the "doing him a solid"-angle, despite my rule of NO BUSINESS WITH FAMILY OR FRIENDS. Lol.
Back to the unit though, it's separate from the main building, has it's own entrance off a pathway, actually WAS a "house" at one time (see:
https://sf.curbed.com/2015/2/24/9988502/rememberin...) before it was moved to this lot, has it's own dedicated yard, I have a reasonably priced contractor that I took care of in 2008 that makes sure I'm taken care of first when there's work, and my business partner will handle almost all the city paperwork. And it looks like I can raise the roof some, so installing a loft will add another 50+ feet of interior space.
In general though, I'm not buying anything in California, I'm actually trying to ready a couple of my places here in San Diego for sale, this was a one-time event, and in the end, the seller is dragging his feet not, it might not even happen lol...